AFNetworking速成教程

本文转载至 http://blog.csdn.net/ysysbaobei/article/details/17390639 

 

 
 
 

转载自：http://www.raywenderlich.com/zh-hans/36079/afnetworking速成教程（1）

 

 

AFNetworking速成教程（1）

Scott Sherwood Scott Sherwood on March 26, 2013

这篇文章还可以在这里找到 英语

Learn how to use AFNetworking: an easy to use network API for iOS!

Learn how to use AFNetworking: an easy to use network API for iOS!

本文是由 iOS Tutorial 小组成员 Scott Sherwood撰写，他是一个基于位置动态加载（Dynamically Loaded）的软件公司（专业的混合定位）的共同创办人。

网络 — 你的程序离开了它就不能生存下去！苹果的Foundation framework中的NSURLConnection又非常难以理解, 不过这里有一个可以使用的替代品：AFNetworking.

AFNetworking 非常受开发者欢迎 – 它赢得了我们读者的青睐：2012年最佳的iOS Library奖（2012 Best iOS Library Award.） 所以现在我就写这篇文章来向你介绍如何在程序中有效的使用它。

AFNetworking 包括了所有你需要与在线资源交互的内容，从web services到文件下载。当你的程序在下载一个大文件期间，AFNetworking还能确保你的UI是可以响应的。

本文将介绍AFNetworking框架主要的组成部分。一路上，你将使用World Weather Online提供的咨询(Feeds)来创建一个天气(Weather)程序。刚开始使用的天气数据是静态的，不过在学完本文内容之后，程序将连接到实时的天气咨询。

今日预计：一个很酷的开发者学习所有关于AFNetworking知识，并在他的程序中使用AFNetworking。我们开始忙活吧！

开始

首先来这里（here）下载本文的启动项目。这个工程提供了一个基本的UI — AFNetworking相关代码还没有添加。

打开MainStoryboard.storyboard文件，将看到3个view controller：

 


从左到右，分别是：

 

  • 顶级(top-level)的导航控制器;
  • 用来显示天气的一个table view controller，每天一行;
  • 一个自定义的view controller (WeatherAnimationViewController) 当用户点击某个table view cell时，这个view controller将显示某一天的天气咨询。

生成并运行项目，你将看到相关的UI出现，但是什么都没有实现！因为程序需要从网络中获取到所需要的数据，而相关代码还没有添加。这也是本文中你将要实现的！

首先，你需要将AFNetworking 框架包含到工程中。如果你还没有AFNetworking的话，在这里下载最新的版本：GitHub.

当你解压出下载的文件后，你将看到其中有一个AFNetworking子文件夹，里面全是.h 和 .m 文件, 如下高亮显示的:

 


将AFNetworking拖拽到Xcode工程中.

 

 


当出现了添加文件的选项时，确保勾选上Copy items into destination group’s folder (if needed) 和 Create groups for any added folders.

 

要完成相关配置，请在工程的Supporting Files群组中打开预编译头文件Weather-Prefix.pch. 然后在别的import后面添加如下一行代码：

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(110,55,26)">#import "AFNetworking.h"</span>  

将AFNetworking添加到预编译头文件，意味着这个框架会被自动的添加到工程的所有源代码文件中。

很容易，不是吗？现在你已经准备好“天气”程序代码了！

操作JSON

AFNetworking通过网络来加载和处理结构化的数据是非常智能的，普通的HTTP请求也一样。尤其是它支持JSON, XML 和 Property Lists (plists).

你可以下载一些JSON数据，然后用自己的解析器来解析，但这何必呢？通过AFNetworking就可以完成这些操作！

 

首先，你需要测试脚本（数据）所需的一个基本URL。将下面的这个静态NSString声明到WTTableViewController.m顶部，也就是所有#import下面：

 

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">static</span> <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">const</span> BaseURLString <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"http://www.raywenderlich.com/downloads/weather_sample/"</span>;  

这个URL是一个非常简单的“web service”，在本文中我特意为你创建的。如果你想知道它看起来是什么样，可以来这里下载代码：download the source.

这个web service以3种不同的格式（JSON, XML 和 PLIST）返回天气数据。你可以使用下面的这些URL来看看返回的数据：

第一个数据格式使用的是JSON. JSON 是一种常见的JavaScript派生类对象格式。看起来如下:

{
    "data": {
        "current_condition": [
            {
                "cloudcover": "16",
                "humidity": "59",
                "observation_time": "09:09 PM",
            }
        ]
    }
}

注意: 如果你想要结更多关于JSON内容，请参考：Working with JSON in iOS 5 Tutorial.

当用户点击程序中的JSON按钮时，你希望对从服务中获得的JSON数据进行加载并处理。在WTTableViewController.m中，找到jsonTapped: 方法 (现在应该是空的) ，并用下面的代码替换：

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>IBAction<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>jsonTapped<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">id</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>sender <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  2.     <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>// 1</em></span>  
  3.     <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>weatherUrl <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> stringWithFormat<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"%@weather.php?format=json"</span>, BaseURLString<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  4.     <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURL_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURL</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>url <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURL_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURL</span></a> URLWithString<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>weatherUrl<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  5.     <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURLRequest_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURLRequest</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>request <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURLRequest_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURLRequest</span></a> requestWithURL<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>url<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  6.    
  7.     <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>// 2</em></span>  
  8.     AFJSONRequestOperation <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>operation <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span>  
  9.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>AFJSONRequestOperation JSONRequestOperationWithRequest<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>request  
  10.         <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>// 3</em></span>  
  11.         success<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:^</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURLRequest_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURLRequest</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>request, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSHTTPURLResponse_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSHTTPURLResponse</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>response, <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">id</span> JSON<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  12.             self.weather  <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSDictionary_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSDictionary</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>JSON;  
  13.             self.title <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"JSON Retrieved"</span>;  
  14.             <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.tableView reloadData<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  15.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  16.         <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>// 4</em></span>  
  17.         failure<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:^</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURLRequest_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURLRequest</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>request, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSHTTPURLResponse_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSHTTPURLResponse</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>response, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSError_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSError</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>error, <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">id</span> JSON<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  18.             UIAlertView <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>av <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>UIAlertView alloc<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span> initWithTitle<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"Error Retrieving Weather"</span>  
  19.                                                          message<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> stringWithFormat<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"%@"</span>,error<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>  
  20.                                                         delegate<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">nil</span>  
  21.                                                cancelButtonTitle<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"OK"</span> otherButtonTitles<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">nil</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  22.             <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>av show<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  23.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  24.    
  25.     <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>// 5</em></span>  
  26.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>operation start<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  27. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  

这是你的第一个AFNetworking代码！因此，这看起来是全新的，我将对这个方法中代码进行介绍。

  1. 根据基本的URL构造出完整的一个URL。然后通过这个完整的URL获得一个NSURL对象，然后根据这个url获得一个NSURLRequest.
  2. AFJSONRequestOperation 是一个功能完整的类（all-in-one）— 整合了从网络中获取数据并对JSON进行解析。
  3. 当请求成功，则运行成功块（success block）。在本示例中，把解析出来的天气数据从JSON变量转换为一个字典（dictionary），并将其存储在属性 weather 中.
  4. 如果运行出问题了，则运行失败块（failure block），比如网络不可用。如果failure block被调用了，将会通过提示框显示出错误信息。

如上所示，AFNetworking的使用非常简单。如果要用苹果提供的APIs（如NSURLConnection）来实现同样的功能（下载和解析JSON数据），则需要许多代码才能做到。

现在天气数据已经存在于self.weather中，你需要将其显示出来。找到tableView:numberOfRowsInSection: 方法，并用下面的代码替换：

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>NSInteger<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>tableView<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>UITableView <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>tableView numberOfRowsInSection<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>NSInteger<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>section  
  2. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  3.     <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>// Return the number of rows in the section.</em></span>  
  4.    
  5.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">if</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">!</span>self.weather<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>  
  6.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">return</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(36,0,217)">0</span>;  
  7.    
  8.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">switch</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>section<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  9.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">case</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(36,0,217)">0</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  10.             <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">return</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(36,0,217)">1</span>;  
  11.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  12.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">case</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(36,0,217)">1</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  13.             <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSArray_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSArray</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>upcomingWeather <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.weather upcomingWeather<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  14.             <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">return</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>upcomingWeather count<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  15.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  16.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">default</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>  
  17.             <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">return</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(36,0,217)">0</span>;  
  18.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  19. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  

table view有两个section：第一个用来显示当前天气，第二个用来显示未来的天气。

等一分钟，你可能正在思考。这里的 [self.weather upcomingWeather]是什么? 如果self.weather是一个普通的NSDictionary, 它是怎么知道 “upcomingWeather” 是什么呢?

为了更容易的解析数据，在starter工程中，有一对NSDictionary categories：

  • NSDictionary+weather.m
  • NSDictionary+weather_package.m

这些categories添加了一些方便的方法，通过这些方法可以很方便的对字典中的数据元素进行访问。这样你就可以专注于网络部分，而不是NSDictionary中数据的访问。对吧？

回到 WTTableViewController.m, 找到 tableView:cellForRowAtIndexPath: 方法，并用下面的实现替换：

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>UITableViewCell <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>tableView<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>UITableView <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>tableView cellForRowAtIndexPath<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSIndexPath_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSIndexPath</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>indexPath  
  2. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  3.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">static</span> <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>CellIdentifier <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"WeatherCell"</span>;  
  4.     UITableViewCell <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>cell <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>tableView dequeueReusableCellWithIdentifier<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>CellIdentifier forIndexPath<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>indexPath<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  5.     <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSDictionary_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSDictionary</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>daysWeather;  
  6.    
  7.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">switch</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>indexPath.section<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  8.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">case</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(36,0,217)">0</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  9.             daysWeather <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.weather currentCondition<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  10.             <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">break</span>;  
  11.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  12.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">case</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(36,0,217)">1</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  13.             <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSArray_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSArray</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>upcomingWeather <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.weather upcomingWeather<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  14.             daysWeather <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>upcomingWeather objectAtIndex<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>indexPath.row<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  15.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  16.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">default</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>  
  17.             <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">break</span>;  
  18.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  19.    
  20.     cell.textLabel.text <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>daysWeather weatherDescription<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  21.    
  22.     <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>// maybe some code will be added here later...</em></span>  
  23.    
  24.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">return</span> cell;  
  25. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  

跟tableView:numberOfRowsInSection: 方法一样，在这里使用了便利的NSDictionary categories来获得数据。当前天的天气是一个字典，而未来几日的天气则存储在一个数组中。

生成并运行工程，然后点击JSON按钮. 这将会动态的获得一个AFJSONOperation对象, 并看到如下画面内容：

 


JSON 操作成功!

 

操作Property Lists(plists)

Property lists (或简称为 plists) 是以确定的格式（苹果定义的）构成的XML文件。苹果一般将plists用在用户设置中。看起来如下：

<dict>
  <key>data</key>
  <dict>
    <key>current_condition</key>
      <array>
      <dict>
        <key>cloudcover</key>
        <string>16</string>
        <key>humidity</key>
        <string>59</string>

上面的意思是：

  • 一个字典中有一个名为“data”的key，这个key对应着另外一个字典。
  • 这个字典有一个名为 “current_condition” 的key，这个key对应着一个array.
  • 这个数组包含着一个字典，字典中有多个key和values。比如cloudcover=16和humidity=59.

现在是时候加载plist版本的天气数据了！找到plistTapped: 方法，并用下面的实现替换：

[objc] view plaincopy
  1.  <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>IBAction<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>plistTapped<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">id</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>sender<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  2.     <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>weatherUrl <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> stringWithFormat<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"%@weather.php?format=plist"</span>,BaseURLString<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  3.     <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURL_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURL</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>url <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURL_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURL</span></a> URLWithString<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>weatherUrl<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  4.     <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURLRequest_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURLRequest</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>request <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURLRequest_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURLRequest</span></a> requestWithURL<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>url<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  5.    
  6.     AFPropertyListRequestOperation <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>operation <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span>  
  7.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>AFPropertyListRequestOperation propertyListRequestOperationWithRequest<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>request  
  8.         success<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:^</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURLRequest_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURLRequest</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>request, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSHTTPURLResponse_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSHTTPURLResponse</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>response, <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">id</span> propertyList<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  9.             self.weather  <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSDictionary_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSDictionary</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>propertyList;  
  10.             self.title <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"PLIST Retrieved"</span>;  
  11.             <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.tableView reloadData<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  12.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  13.         failure<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:^</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURLRequest_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURLRequest</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>request, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSHTTPURLResponse_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSHTTPURLResponse</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>response, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSError_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSError</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>error, <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">id</span> propertyList<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  14.             UIAlertView <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>av <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>UIAlertView alloc<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span> initWithTitle<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"Error Retrieving Weather"</span>  
  15.                               message<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> stringWithFormat<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"%@"</span>,error<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>  
  16.                                                         delegate<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">nil</span>  
  17.                                                cancelButtonTitle<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"OK"</span>  
  18.                                                otherButtonTitles<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">nil</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  19.             <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>av show<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  20.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  21.    
  22.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>operation start<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  23. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  

注意到，上面的代码几乎与JSON版的一致，只不过将操作（operation）的类型从AFJSONOperation 修改为 AFPropertyListOperation. 这非常的整齐：你才程序只需要修改一丁点代码就可以接收JSON或plist格式的数据了！

生成并运行工程，然后点击PLIST按钮。将看到如下内容：

 


如果你需要重置所有的内容，以重新开始操作，导航栏顶部的Clear按钮可以清除掉title和table view中的数据。

 

操作XML

AFNetworking处理JSON和plist的解析使用的是类似的方法，并不需要花费太多功夫，而处理XML则要稍微复杂一点。下面，就根据XML咨询构造一个天气字典（NSDictionary）。

iOS提供了一个帮助类：NSXMLParse (如果你想了解更多内容，请看这里的链接：SAX parser).

还是在文件WTTableViewController.m, 找到 xmlTapped: 方法，并用下面的实现替换：

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>IBAction<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>xmlTapped<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">id</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>sender<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  2.     <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>weatherUrl <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> stringWithFormat<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"%@weather.php?format=xml"</span>,BaseURLString<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  3.     <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURL_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURL</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>url <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURL_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURL</span></a> URLWithString<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>weatherUrl<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  4.     <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURLRequest_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURLRequest</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>request <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURLRequest_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURLRequest</span></a> requestWithURL<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>url<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  5.    
  6.     AFXMLRequestOperation <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>operation <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span>  
  7.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>AFXMLRequestOperation XMLParserRequestOperationWithRequest<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>request  
  8.         success<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:^</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURLRequest_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURLRequest</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>request, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSHTTPURLResponse_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSHTTPURLResponse</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>response, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSXMLParser_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSXMLParser</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>XMLParser<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  9.             <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>//self.xmlWeather = [NSMutableDictionary dictionary];</em></span>  
  10.             XMLParser.delegate <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> self;  
  11.             <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>XMLParser setShouldProcessNamespaces<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">YES</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  12.             <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>XMLParser parse<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  13.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  14.         failure<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:^</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURLRequest_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURLRequest</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>request, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSHTTPURLResponse_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSHTTPURLResponse</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>response, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSError_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSError</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>error, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSXMLParser_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSXMLParser</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>XMLParser<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  15.             UIAlertView <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>av <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>UIAlertView alloc<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span> initWithTitle<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"Error Retrieving Weather"</span>  
  16.                                                          message<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> stringWithFormat<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"%@"</span>,error<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>  
  17.                                                         delegate<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">nil</span>  
  18.                                                cancelButtonTitle<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"OK"</span>  
  19.                                                otherButtonTitles<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">nil</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  20.             <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>av show<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  21.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  22.    
  23.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>operation start<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  24. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  

到现在为止，这看起来跟之前处理JSON和plist很类似。最大的改动就是在成功块（success block）中, 在这里不会传递给你一个预处理好的NSDictionary对象. 而是AFXMLRequestOperation实例化的NSXMLParse对象，这个对象将用来处理繁重的XML解析任务。

NSXMLParse对象有一组delegate方法是你需要实现的 — 用来获得XML数据。注意，在上面的代码中我将XMLParser的delegate设置为self, 因此WTTableViewController将用来处理XML的解析任务。

首先，更新一下WTTableViewController.h 并修改一下类声明，如下所示：

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">@interface</span> WTTableViewController <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span> UITableViewController<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">&</span>lt;NSXMLParserDelegate<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">&</span>gt;  

上面代码的意思是这个类将实现（遵循）NSXMLParserDelegate协议. 下一步将下面的delegate方法声明添加到@implementation后面:

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">void</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>parser<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSXMLParser_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSXMLParser</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>parser didStartElement<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>elementName namespaceURI<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>namespaceURI qualifiedName<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>qName attributes<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSDictionary_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSDictionary</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>attributeDict;  
  2. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">void</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>parser<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSXMLParser_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSXMLParser</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>parser foundCharacters<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">string</span>;  
  3. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">void</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>parser<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSXMLParser_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSXMLParser</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>parser didEndElement<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>elementName namespaceURI<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>namespaceURI qualifiedName<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>qName;  
  4. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">void</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> parserDidEndDocument<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSXMLParser_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSXMLParser</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>parser;  

为了支持资讯的解析，还需要一些属性来存储相关的数据。将下面的代码添加到@implementatio后面:

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">@property</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>strong<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSMutableDictionary_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSMutableDictionary</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>xmlWeather; <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>//package containing the complete response</em></span>  
  2. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">@property</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>strong<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSMutableDictionary_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSMutableDictionary</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>currentDictionary; <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>//current section being parsed</em></span>  
  3. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">@property</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>strong<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>previousElementName;  
  4. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">@property</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>strong<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>elementName;  
  5. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">@property</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>strong<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSMutableString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSMutableString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>outstring;  

接着打开WTTableViewController.m，现在你需要一个一个的实现上面所说的几个delegate方法。将下面这个方法粘贴到实现文件中：

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">void</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>parser<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSXMLParser_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSXMLParser</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>parser didStartElement<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>elementName namespaceURI<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>namespaceURI qualifiedName<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>qName attributes<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSDictionary_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSDictionary</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>attributeDict  <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  2.     self.previousElementName <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> self.elementName;  
  3.    
  4.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">if</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>qName<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  5.         self.elementName <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> qName;  
  6.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  7.    
  8.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">if</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>qName isEqualToString<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"current_condition"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  9.         self.currentDictionary <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSMutableDictionary_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSMutableDictionary</span></a> dictionary<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  10.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  11.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">else</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">if</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>qName isEqualToString<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"weather"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  12.         self.currentDictionary <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSMutableDictionary_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSMutableDictionary</span></a> dictionary<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  13.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  14.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">else</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">if</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>qName isEqualToString<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"request"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  15.         self.currentDictionary <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSMutableDictionary_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSMutableDictionary</span></a> dictionary<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  16.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  17.    
  18.     self.outstring <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSMutableString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSMutableString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">string</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  19. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  

当NSXMLParser发现了新的元素开始标签时，会调用上面这个方法。在这个方法中，在构造一个新字典用来存储赋值给currentDictionary属性之前，首先保存住上一个元素名称。还要将outstring重置一下，这个字符串用来构造XML标签中的数据。

然后将下面这个方法粘贴到上一个方法的后面：

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">void</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>parser<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSXMLParser_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSXMLParser</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>parser foundCharacters<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">string</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  2.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">if</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">!</span>self.elementName<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  3.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">return</span>;  
  4.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  5.    
  6.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.outstring appendFormat<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"%@"</span>, <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">string</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  7. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  

如名字一样，当NSXMLParser在一个XML标签中发现了字符数据，会调用这个方法。该方法将字符数据追加到outstring属性中，当XML标签结束的时候，这个outstring会被处理。

继续，将下面这个方法粘贴到上一个方法的后面：

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">void</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>parser<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSXMLParser_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSXMLParser</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>parser didEndElement<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>elementName namespaceURI<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>namespaceURI qualifiedName<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>qName <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  2.    
  3.     <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>// 1</em></span>  
  4.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">if</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>qName isEqualToString<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"current_condition"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span> ||  
  5.        <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>qName isEqualToString<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"request"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  6.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.xmlWeather setObject<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSArray_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSArray</span></a> arrayWithObject<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>self.currentDictionary<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span> forKey<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>qName<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  7.         self.currentDictionary <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">nil</span>;  
  8.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  9.     <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>// 2</em></span>  
  10.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">else</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">if</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>qName isEqualToString<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"weather"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  11.    
  12.         <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>// Initalise the list of weather items if it dosnt exist</em></span>  
  13.         <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSMutableArray_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSMutableArray</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>array <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.xmlWeather objectForKey<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"weather"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  14.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">if</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">!</span>array<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>  
  15.             array <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSMutableArray_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSMutableArray</span></a> array<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  16.    
  17.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>array addObject<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>self.currentDictionary<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  18.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.xmlWeather setObject<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>array forKey<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"weather"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  19.    
  20.         self.currentDictionary <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">nil</span>;  
  21.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  22.     <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>// 3</em></span>  
  23.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">else</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">if</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>qName isEqualToString<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"value"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  24.         <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>//Ignore value tags they only appear in the two conditions below</em></span>  
  25.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  26.     <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>// 4</em></span>  
  27.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">else</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">if</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>qName isEqualToString<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"weatherDesc"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span> ||  
  28.             <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>qName isEqualToString<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"weatherIconUrl"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  29.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.currentDictionary setObject<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSArray_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSArray</span></a> arrayWithObject<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSDictionary_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSDictionary</span></a> dictionaryWithObject<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>self.outstring forKey<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"value"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span> forKey<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>qName<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  30.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  31.     <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>// 5</em></span>  
  32.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">else</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  33.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.currentDictionary setObject<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>self.outstring forKey<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>qName<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  34.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  35.    
  36.     self.elementName <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">nil</span>;  
  37. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  

当检测到元素的结束标签时，会调用上面这个方法。在这个方法中，会查找一些标签：

  1. urrent_condition 元素表示获得了一个今天的天气。会把今天的天气直接添加到xmlWeather字典中。
  2. weather 元素表示获得了随后一天的天气。今天的天气只有一个，而后续的天气有多个，所以在此，将后续天气添加到一个数组中。
  3. value 标签出现在别的标签中，所以这里可以忽略掉这个标签。
  4. weatherDesc 和 weatherIconUrl 元素的值在存储之前，需要需要被放入一个数组中 — 这里的结构是为了与JSON和plist版本天气咨询格式相匹配。
  5. 所有其它元素都是按照原样（as-is）进行存储的。

下面是最后一个delegate方法！将下面这个方法粘贴到上一个方法的后面：

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">void</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> parserDidEndDocument<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSXMLParser_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSXMLParser</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>parser <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  2.     self.weather <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSDictionary_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSDictionary</span></a> dictionaryWithObject<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>self.xmlWeather forKey<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"data"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  3.     self.title <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"XML Retrieved"</span>;  
  4.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.tableView reloadData<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  5. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  

当NSXMLParser解析到document的尾部时，会调用这个方法。在此，xmlWeather字典已经构造完毕，table view可以重新加载了。

在上面代码中将xmlWeather添加到一个字典中，看起来是冗余的, 不过这样可以确保与JSON和plist版本的格式完全匹配。这样所有的3种数据格式（JSON, plist和XML）都能够用相同的代码来显示！

 

现在所有的delegate方法和属性都搞定了，找到xmlTapped: 方法，并取消注释成功块（success block）中的一行代码：

 

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>IBAction<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>xmlTapped<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">id</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>sender<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  2.     ...  
  3.     success<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:^</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURLRequest_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURLRequest</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>request, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSHTTPURLResponse_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSHTTPURLResponse</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>response, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSXMLParser_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSXMLParser</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>XMLParser<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  4.         <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>// the line below used to be commented out</em></span>  
  5.         self.xmlWeather <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSMutableDictionary_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSMutableDictionary</span></a> dictionary<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  6.         XMLParser.delegate <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> self;  
  7.     ...  
  8. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  

生成和运行工程，然后点击XML按钮，将看到如下内容：

 


 

一个小的天气程序

嗯, 上面的这个程序看起来体验不太友好，有点像整周都是阴雨天。如何让table view中的天气信息体验更好点呢？

再仔细看看之前的JSON格式数据：JSON format from before，你会看到每个天气项里面都有一个图片URLs。 将这些天气图片显示到每个table view cell中，这样程序看起来会更有意思。

AFNetworking给UIImageView添加了一个category，让图片能够异步加载，也就是说当图片在后台下载的时候，程序的UI界面仍然能够响应。为了使用这个功能，首先需要将这个category import到WTTableViewController.m文件的顶部：

#import "UIImageView+AFNetworking.h"
找到tableView:cellForRowAtIndexPath: 方法，并将下面的代码粘贴到最后的return cell; 代码上上面（这里应该有一个注释标记）
[objc] view plaincopy
  1. __weak UITableViewCell <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>weakCell <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> cell;  
  2.    
  3. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>cell.imageView setImageWithURLRequest<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURLRequest_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURLRequest</span></a> alloc<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span> initWithURL<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURL_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURL</span></a> URLWithString<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>daysWeather.weatherIconURL<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>  
  4.                       placeholderImage<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>UIImage imageNamed<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"placeholder.png"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>  
  5.                                success<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:^</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURLRequest_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURLRequest</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>request, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSHTTPURLResponse_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSHTTPURLResponse</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>response, UIImage <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>image<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  6.                                    weakCell.imageView.image <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> image;  
  7.    
  8.                                    <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>//only required if no placeholder is set to force the imageview on the cell to be laid out to house the new image.</em></span>  
  9.                                    <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>//if(weakCell.imageView.frame.size.height==0 || weakCell.imageView.frame.size.width==0 ){</em></span>  
  10.                                    <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>weakCell setNeedsLayout<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  11.                                    <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>//}</em></span>  
  12.                                <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  13.                                failure<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:^</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURLRequest_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURLRequest</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>request, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSHTTPURLResponse_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSHTTPURLResponse</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>response, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSError_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSError</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>error<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  14.    
  15.                                <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  

首先创建一个弱引用(weak)的cell，这样就可以在block中使用这个cell。如果你直接访问cell变量，Xcode会提示一个关于retain循环和内存泄露的警告。

UIImageView+AFNetworking category定义了一个setImageWithURLRequest… 方法. 这个方法的参数包括：一个指向图片URL的请求，一个占位符图片，一个success block和一个failure block。

当cell首次被创建的时候，cell中的UIImageView将显示一个占位符图片，直到真正的图片被下载完成。在这里你需要确保占位符的图片与实际图片尺寸大小相同。

如果尺寸不相同的话，你可以在success block中调用cell的setNeedsLayout方法. 上面代码中对两行代码进行了注释，这是因为这里的占位符图片尺寸正好合适，留着注释，可能在别的程序中需要用到。

现在生成并运行工程，然后点击之前添加的3个操作中的任意一个，将看到如下内容：

 


很好! 异步加载图片从来没有这么简单过。

 

一个RESTful类

到现在你已经使用类似AFJSONRequestOperation这样的类创建了一次性的HTTP请求。另外，较低级的AFHTTPClient类是用来访问单个的web service终端。 对这个AFHTTPClient一般是给它设置一个基本的URL，然后用AFHTTPClient进行多个请求（而不是像之前的那样，每次请求的时候，都创建一个AFHTTPClient）。

AFHTTPClient同样为编码参数、处理multipart表单请求body的构造、管理请求操作和批次入队列操作提供了很强的灵活性，它还处理了整套RESTful (GET, POST, PUT, 和 DELETE), 下面我们就来试试最常用的两个：GET 和 POST.

注意: 对REST, GET和POST不清楚？看看这里比较有趣的介绍 – 我如何给妻子解释REST(How I Explained REST to My Wife.)

在WTTableViewController.h 顶部将类声明按照如下修改：

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">@interface</span> WTTableViewController <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span> UITableViewController  

在 WTTableViewController.m中，找到httpClientTapped: 方法，并用下面的实现替换：

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>IBAction<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>httpClientTapped<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">id</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>sender <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  2.     UIActionSheet <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>actionSheet <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>UIActionSheet alloc<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span> initWithTitle<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"AFHTTPClient"</span> delegate<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>self cancelButtonTitle<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"Cancel"</span> destructiveButtonTitle<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">nil</span> otherButtonTitles<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"HTTP POST"</span>,<span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"HTTP GET"</span>, <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">nil</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  3.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>actionSheet showFromBarButtonItem<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>sender animated<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">YES</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  4. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  

上面的方法会弹出一个action sheet，用以选择GET和POST请求。粘贴如下代码以实现action sheet中按钮对应的操作：

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">void</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>actionSheet<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>UIActionSheet <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>actionSheet clickedButtonAtIndex<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>NSInteger<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>buttonIndex<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  2.     <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>// 1</em></span>  
  3.     <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURL_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURL</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>baseURL <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURL_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURL</span></a> URLWithString<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> stringWithFormat<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>BaseURLString<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  4.     <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSDictionary_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSDictionary</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>parameters <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSDictionary_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSDictionary</span></a> dictionaryWithObject<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"json"</span> forKey<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"format"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  5.    
  6.     <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>// 2</em></span>  
  7.     AFHTTPClient <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>client <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>AFHTTPClient alloc<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span> initWithBaseURL<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>baseURL<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  8.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>client registerHTTPOperationClass<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>AFJSONRequestOperation class<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  9.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>client setDefaultHeader<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"Accept"</span> value<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"application/json"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  10.    
  11.     <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>// 3</em></span>  
  12.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">if</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>buttonIndex<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">==</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(36,0,217)">0</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  13.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>client postPath<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"weather.php"</span>  
  14.               parameters<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>parameters  
  15.                  success<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:^</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>AFHTTPRequestOperation <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>operation, <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">id</span> responseObject<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  16.                      self.weather <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> responseObject;  
  17.                      self.title <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"HTTP POST"</span>;  
  18.                      <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.tableView reloadData<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  19.                  <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  20.                  failure<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:^</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>AFHTTPRequestOperation <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>operation, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSError_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSError</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>error<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  21.                      UIAlertView <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>av <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>UIAlertView alloc<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span> initWithTitle<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"Error Retrieving Weather"</span>  
  22.                                                                   message<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> stringWithFormat<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"%@"</span>,error<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>  
  23.                                                                  delegate<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">nil</span>  
  24.                                                         cancelButtonTitle<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"OK"</span> otherButtonTitles<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">nil</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  25.                      <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>av show<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  26.    
  27.                  <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  28.          <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  29.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  30.     <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>// 4</em></span>  
  31.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">else</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">if</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>buttonIndex<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">==</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(36,0,217)">1</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  32.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>client getPath<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"weather.php"</span>  
  33.              parameters<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>parameters  
  34.                 success<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:^</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>AFHTTPRequestOperation <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>operation, <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">id</span> responseObject<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  35.                     self.weather <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> responseObject;  
  36.                     self.title <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"HTTP GET"</span>;  
  37.                     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.tableView reloadData<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  38.                 <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  39.                 failure<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:^</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>AFHTTPRequestOperation <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>operation, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSError_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSError</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>error<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  40.                     UIAlertView <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>av <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>UIAlertView alloc<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span> initWithTitle<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"Error Retrieving Weather"</span>  
  41.                                                                  message<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> stringWithFormat<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"%@"</span>,error<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>  
  42.                                                                 delegate<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">nil</span>  
  43.                                                        cancelButtonTitle<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"OK"</span> otherButtonTitles<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">nil</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  44.                     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>av show<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  45.    
  46.                 <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  47.          <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  48.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  49. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  

上面的代码作用如下:

  1. 构建一个baseURL，以及一个参数字典，并将这两个变量传给AFHTTPClient.
  2. 将AFJSONRequestOperation注册为HTTP的操作, 这样就可以跟之前的示例一样，可以获得解析好的JSON数据。
  3. 做了一个GET请求，这个请求有一对block：success和failure。
  4. POST请求跟GET一样。

在这里，将请求一个JSON回应，当然也可以使用之前讨论过的另外两种格式来代替JSON。

生成并运行工程，点击HTTPClient按钮，然后选择GET 或 POST按钮来初始化一个相关的请求。之后会看到如下内容：

 


至此，你已经知道AFHTTPClient最基本的使用方法。不过，这里还有更好的一种使用方法，它可以让代码更加干净整齐，下面我们就来学习一下吧。

 

连接到Live Service

到现在为止，你已经在table view controller中直接调用了AFRequestOperations 和 AFHTTPClient. 实际上，大多数时候不是这样的，你的网络请求会跟某个web service或API相关。

AFHTTPClient已经具备与web API通讯的所有内容。AFHTTPClient在代码中已经把网络通讯部分做了解耦处理，让网络通讯的代码在整个工程中都可以重用。

下面是两个关于AFHTTPClient最佳实践的指导：

  1. 为每个web service创建一个子类。例如，如果你在写一个社交网络聚合器，那么可能就会有Twitter的一个子类，Facebook的一个子类，Instragram的一个子类等等。
  2. 在AFHTTPClient子类中，创建一个类方法，用来返回一个共享的单例，这将会节约资源并省去必要的对象创建。

当前，你的工程中还没有一个AFHTTPClient的子类，下面就来创建一个吧。我们来处理一下，让代码清洁起来。

首先，在工程中创建一个新的文件：iOSCocoa TouchObjective-C Class. 命名为WeatherHTTPClient 并让其继承自AFHTTPClient.

你希望这个类做3件事情：

A：执行HTTP请求

B：当有新的可用天气数据时，调用delegate

C：使用用户当前地理位置来获得准确的天气。

用下面的代码替换WeatherHTTPClient.h:

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(110,55,26)">#import "AFHTTPClient.h"</span>  
  2.    
  3. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">@protocol</span> WeatherHttpClientDelegate;  
  4.    
  5. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">@interface</span> WeatherHTTPClient <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span> AFHTTPClient  
  6.    
  7. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">@property</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>weak<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">id</span> delegate;  
  8.    
  9. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">+</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>WeatherHTTPClient <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>sharedWeatherHTTPClient;  
  10. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">id</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>initWithBaseURL<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURL_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURL</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>url;  
  11. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">void</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>updateWeatherAtLocation<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>CLLocation <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>location forNumberOfDays<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">int</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>number;  
  12.    
  13. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">@end</span>  
  14.    
  15. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">@protocol</span> WeatherHttpClientDelegate   
  16. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">void</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>weatherHTTPClient<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>WeatherHTTPClient <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>client didUpdateWithWeather<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">id</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>weather;  
  17. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">void</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>weatherHTTPClient<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>WeatherHTTPClient <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>client didFailWithError<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSError_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSError</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>error;  
  18. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">@end</span>  

在实现文件中，你将了解头文件中定义的更多相关内容。打开WeatherHTTPClient.m 并将下面的代码添加到@implementation下面:

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">+</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>WeatherHTTPClient <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>sharedWeatherHTTPClient  
  2. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  3.     <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>urlStr <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"http://free.worldweatheronline.com/feed/"</span>;  
  4.    
  5.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">static</span> dispatch_once_t pred;  
  6.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">static</span> WeatherHTTPClient <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>_sharedWeatherHTTPClient <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">nil</span>;  
  7.    
  8.     dispatch_once<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">&</span>amp;pred, <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">^</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span> _sharedWeatherHTTPClient <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self alloc<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span> initWithBaseURL<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURL_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURL</span></a> URLWithString<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>urlStr<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>; <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>;  
  9.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">return</span> _sharedWeatherHTTPClient;  
  10. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  11.    
  12. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">id</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>initWithBaseURL<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURL_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURL</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>url  
  13. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  14.     self <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>super initWithBaseURL<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>url<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  15.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">if</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">!</span>self<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  16.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">return</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">nil</span>;  
  17.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  18.    
  19.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self registerHTTPOperationClass<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>AFJSONRequestOperation class<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  20.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self setDefaultHeader<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"Accept"</span> value<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"application/json"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  21.    
  22.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">return</span> self;  
  23. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  

sharedWeatherHTTPClient 方法使用Grand Central Dispatch（GCD）来确保这个共享的单例对象只被初始化分配一次。这里用一个base URL来初始化对象，并将其设置为期望web service响应为JSON。

将下面的方法粘贴到上一个方法的下面：

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">void</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>updateWeatherAtLocation<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>CLLocation <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>location forNumberOfDays<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">int</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>number<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  2.     <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSMutableDictionary_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSMutableDictionary</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>parameters <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSMutableDictionary_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSMutableDictionary</span></a> dictionary<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  3.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>parameters setObject<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> stringWithFormat<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"%d"</span>,number<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span> forKey<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"num_of_days"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  4.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>parameters setObject<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> stringWithFormat<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"%f,%f"</span>,location.coordinate.latitude,location.coordinate.longitude<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span> forKey<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"q"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  5.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>parameters setObject<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"json"</span> forKey<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"format"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  6.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>parameters setObject<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"7f3a3480fc162445131401"</span> forKey<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"key"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  7.    
  8.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self getPath<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"weather.ashx"</span>  
  9.        parameters<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>parameters  
  10.           success<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:^</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>AFHTTPRequestOperation <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>operation, <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">id</span> responseObject<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  11.             <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">if</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.delegate respondsToSelector<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">@selector</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>weatherHTTPClient<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>didUpdateWithWeather<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>  
  12.                 <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.delegate weatherHTTPClient<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>self didUpdateWithWeather<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>responseObject<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  13.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  14.         failure<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:^</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>AFHTTPRequestOperation <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>operation, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSError_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSError</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>error<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  15.             <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">if</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.delegate respondsToSelector<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">@selector</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>weatherHTTPClient<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>didFailWithError<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>  
  16.                 <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.delegate weatherHTTPClient<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>self didFailWithError<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>error<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  17.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  18. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  

这个方法调用World Weather Online接口，以获得具体位置的天气信息。

非常重要！本实例中的API key仅仅是为本文创建的。如果你创建了一个程序，请在World Weather Online创建一个账号，并获得你自己的API key！

一旦对象获得了天气数据，它需要一些方法来通知对此感兴趣的对象：数据回来了。这里要感谢WeatherHttpClientDelegate 协议和它的delegate方法，在上面代码中的success 和 failure blocks可以通知一个controller：指定位置的天气已经更新了。这样，controller就可以对天气做更新显示。

现在，我们需要把这些代码片段整合到一起！WeatherHTTPClient希望接收一个位置信息，并且WeatherHTTPClient定义了一个delegate协议，现在对WTTableViewControlle类做一下更新，以使用WeatherHTTPClient.

打开WTTableViewController.h 添加一个import，并用下面的代码替换@interface声明:

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(110,55,26)">#import "WeatherHTTPClient.h"</span>  
  2.    
  3. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">@interface</span> WTTableViewController <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span> UITableViewController  

另外添加一个新的Core Location manager 属性:

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">@property</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>strong<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> CLLocationManager <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>manager;  

在 WTTableViewController.m中，将下面的代码添加到viewDidLoad:的底部：

[objc] view plaincopy
  1. self.manager <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>CLLocationManager alloc<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span> init<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  2. self.manager.delegate <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> self;  

上面这两行代码初始化了Core Location manager，这样当view加载的时候，用来确定用户的当前位置。Core Location然后会通过delegate回调以传回位置信息。将下面的方法添加到实现文件中：

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">void</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>locationManager<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>CLLocationManager <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>manager didUpdateToLocation<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>CLLocation <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>newLocation fromLocation<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>CLLocation <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>oldLocation<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  2.    
  3.     <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>//if the location is more than 5 minutes old ignore</em></span>  
  4.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">if</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>newLocation.timestamp timeIntervalSinceNow<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">&</span>lt; <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(36,0,217)">300</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  5.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.manager stopUpdatingLocation<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  6.    
  7.         WeatherHTTPClient <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>client <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>WeatherHTTPClient sharedWeatherHTTPClient<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  8.         client.delegate <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> self;  
  9.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>client updateWeatherAtLocation<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>newLocation forNumberOfDays<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(36,0,217)">5</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;    
  10.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  11. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  

现在，当用户的位置有了变化时，你就可以使用WeatherHTTPClient单例来请求当前位置的天气信息。

记住，WeatherHTTPClient有两个delegate方法需要实现。将下面两个方法添加到实现文件中：

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">void</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>weatherHTTPClient<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>WeatherHTTPClient <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>client didUpdateWithWeather<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">id</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>aWeather<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  2.     self.weather <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> aWeather;  
  3.     self.title <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"API Updated"</span>;  
  4.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.tableView reloadData<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  5. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  6.    
  7. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">void</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>weatherHTTPClient<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>WeatherHTTPClient <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>client didFailWithError<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSError_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSError</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>error<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  8.     UIAlertView <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>av <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>UIAlertView alloc<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span> initWithTitle<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"Error Retrieving Weather"</span>  
  9.                                                  message<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> stringWithFormat<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"%@"</span>,error<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>  
  10.                                                 delegate<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">nil</span>  
  11.                                        cancelButtonTitle<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"OK"</span> otherButtonTitles<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">nil</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  12.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>av show<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  13. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  

上面的两个方法，当WeatherHTTPClient请求成功, 你就可以更新天气数据并重新加载table view。如果网络错误，则显示一个错误信息。

找到apiTapped: 方法，并用下面的方法替换：

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>IBAction<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>apiTapped<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">id</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>sender<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  2.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.manager startUpdatingLocation<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  3. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  

生成并运行程序，点击AP按钮以初始化一个WeatherHTTPClient 请求, 然后会看到如下画面:

 


希望在这里你未来的天气跟我的一样：晴天！

 

我还没有死！

你可能注意到了，这里调用的外部web service需要花费一些时间才能返回数据。当在进行网络操作时，给用户提供一个信息反馈是非常重要的，这样用户才知道程序是在运行中或已奔溃了。

 

很幸运的是，AFNetworking有一个简便的方法来提供信息反馈：AFNetworkActivityIndicatorManager.

 

在 WTAppDelegate.m中，找到application:didFinishLaunchingWithOptions: 方法，并用下面的方法替换：

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">BOOL</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>application<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>UIApplication <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>application didFinishLaunchingWithOptions<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSDictionary_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSDictionary</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>launchOptions  
  2. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  3.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>AFNetworkActivityIndicatorManager sharedManager<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>.enabled <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">YES</span>;  
  4.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">return</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">YES</span>;  
  5. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  

让sharedManager可以自动的显示出网络活动指示器（ network activity indicator）— 无论射门时候，只要有一个新的网络请求在后台运行着。 这样你就不需要每次请求的时候，都要单独进行管理。

生成并运行工程，无论什么时候，只要有网络请求，都可以在状态栏中看到一个小的网络风火轮：

 


现在，即使你的程序在等待一个很慢的web service，用户都知道程序还在运行着!

 

下载图片

如果你在table view cell上点击，程序会切换到天气的详细画面，并且以动画的方式显示出相应的天气情况。

这非常不错，但目前动画只有一个背景图片。除了通过网络来更新背景图片，还有更好的方法吗！

下面是本文关于介绍AFNetworking的最后内容了：AFImageRequestOperation. 跟AFJSONRequestOperation一样, AFImageRequestOperation封装了HTTP请求：获取图片。

在WeatherAnimationViewController.m 中有两个方法需要实现. 找到updateBackgroundImage: 方法，并用下面的代码替换:

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>IBAction<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>updateBackgroundImage<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">id</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>sender <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  2.    
  3.     <span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>//Store this image on the same server as the weather canned files</em></span>  
  4.     <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURLRequest_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURLRequest</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>request <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURLRequest_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURLRequest</span></a> requestWithURL<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURL_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURL</span></a> URLWithString<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"http://www.scott-sherwood.com/wp-content/uploads/2013/01/scene.png"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  5.     AFImageRequestOperation <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>operation <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>AFImageRequestOperation imageRequestOperationWithRequest<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>request  
  6.         imageProcessingBlock<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">nil</span>  
  7.         success<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:^</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURLRequest_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURLRequest</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>request, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSHTTPURLResponse_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSHTTPURLResponse</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>response, UIImage <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>image<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  8.             self.backgroundImageView.image <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> image;  
  9.             <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self saveImage<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>image withFilename<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"background.png"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  10.         <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  
  11.         failure<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:^</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSURLRequest_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSURLRequest</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>request, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSHTTPURLResponse_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSHTTPURLResponse</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>response, <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSError_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSError</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>error<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  12.             NSLog<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"Error %@"</span>,error<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>;  
  13.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  14.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>operation start<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  15. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  

这个方法初始化并下载一个新的背景图片。在结束时，它将返回请求到的完整图片。

在WeatherAnimationViewController.m中, 你将看到两个辅助方法：imageWithFilename: 和 saveImage:withFilename:, 通过这两个辅助方法，可以对下载下来的图片进行存储和加载。updateBackgroundImage: 将通过辅助方法把下载的图片存储到磁盘中。

接下来找到deleteBackgroundImage: 方法，并用下面的代码替换:

[objc] view plaincopy
  1. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">-</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>IBAction<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>deleteBackgroundImage<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">id</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>sender <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">{</span>  
  2.     <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>path;  
  3.     <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSArray_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSArray</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>paths <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> NSSearchPathForDirectoriesInDomains<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">(</span>NSDocumentDirectory, NSUserDomainMask, <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(166,19,144)">YES</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">)</span>;  
  4.     path <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>paths objectAtIndex<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(36,0,217)">0</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span> stringByAppendingPathComponent<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span><span style="border:0px; font-family:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(17,116,10)"><em>@</em></span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(191,29,26)">"WeatherHTTPClientImages/"</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  5.    
  6.     <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSError_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSError</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>error;  
  7.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span><a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSFileManager_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSFileManager</span></a> defaultManager<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span> removeItemAtPath<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>path error<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:&</span>amp;error<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  8.    
  9.     <a target="_blank" href="http://developer.apple.com/documentation/Cocoa/Reference/Foundation/Classes/NSString_Class/" style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,104,55)"><span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(64,0,128)">NSString</span></a> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">*</span>desc <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">=</span> <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self.weatherDictionary weatherDescription<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  10.     <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">[</span>self start<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">:</span>desc<span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">]</span>;  
  11. <span style="border:0px; font-family:inherit; font-style:inherit; margin:0px; outline:0px; padding:0px; vertical-align:baseline; color:rgb(0,34,0)">}</span>  

这个方法将删除已经下载的图片，这样在测试程序的时候，你可以再次下载图片。

最后一次：生成并运行工程，下载天气数据，并点击某个cell，以打开详细天气画面。在详细天气画面中，点击Update Background 按钮. 如果你点击的是晴天cell，将会看到如下画面：

 


 

以上就是本文的第一部分内容，第二部分内容在这里：AFNetworking速成教程（2）

posted @ 2014-12-21 16:34  天牛  阅读(289)  评论(0)  编辑  收藏  举报