ios开发 简易的天气应用(GET、XML)

1.新建Empty Application，添加UIViewController视图，视图设计如下：

 

 //  HomeViewController.h

//  WeatherQuery


#import <UIKit/UIKit.h>

@interface HomeViewController : UIViewController<UIApplicationDelegate, UISearchBarDelegate>
{
    NSMutableData *data;//用于接收服务器返回的结果
    NSMutableArray *Elements;//对服务器返回结果处理后所有XML元素里面的文字
    NSString *Element;//解析XML某个元素时存储其中的文字，这个元素解析完后Element后，被加到Elements中
}

@property (retain, nonatomic) IBOutlet UILabel *city;
@property (retain, nonatomic) IBOutlet UILabel *date;
@property (retain, nonatomic) IBOutlet UITextView *detail;

@end

API：

 

思路：获取数据，接收数据，解析数据，显示数据

//  HomeViewController.m
//  WeatherQuery


#import "HomeViewController.h"

@interface HomeViewController ()

@end

@implementation HomeViewController

@synthesize city;
@synthesize date;
@synthesize detail;

//UISearchBarDelegate协议的响应事件
- (void)searchBarSearchButtonClicked:(UISearchBar *)searchBar
{
   [searchBar resignFirstResponder];
    NSString *search = searchBar.text;
    NSString *urlString = [@"http://www.webxml.com.cn/WebServices/WeatherWS.asmx/getWeather?theUserID=xxxxxxxx&theCityCode=" stringByAppendingString:search];
    //在生成NSURL对象时，需要调用NSString的stringByAppendingString
    NSURL *url = [NSURL URLWithString:[urlString stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding]];
    NSURLRequest *request = [[NSURLRequest alloc] initWithURL:url cachePolicy:NSURLRequestReturnCacheDataElseLoad timeoutInterval:60.0];
    
    data = [[NSMutableData data] retain];
    [NSURLConnection connectionWithRequest:request delegate:self];
}

//收到响应时，将data长度初始化为0
- (void)connection:(NSURLConnection *)connection didReceiveResponse:(NSURLResponse *)response
{
    [data setLength:0];
}

//当接收到数据后，把数据加到data后面
- (void)connection:(NSURLConnection *)connection didReceiveData:(NSData *)incomingData
{
    [data appendData:incomingData];
}

//数据传送完毕，使用NSXMLParser对数据进行解析
- (void)connectionDidFinishLoading:(NSURLConnection *)connection
{
    NSXMLParser *parser = [[NSXMLParser alloc] initWithData:data];
    [parser setDelegate:self];
    Elements = [NSMutableArray arrayWithCapacity:0];
    [parser parse];
    [parser release];
    [data release];
}

//连接失败，输出日志并释放data对象
- (void)connection:(NSURLConnection *)connection didFailWithError:(NSError *)error
{
    NSLog(@"天气查询出错：%@", [error localizedDescription]);
    [data release];
}

//开始对一个XML元素进行解析，将Element初始化为空字符串
- (void)parser:(NSXMLParser *)parser didStartElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName attributes:(NSDictionary *)attributeDict
{
    Element = @"";
}

//对一个XML元素解析完成，将Element加到Elements数组中
- (void)parser:(NSXMLParser *)parser didEndElement:(NSString *)elementName namespaceURI:(NSString *)namespaceURI qualifiedName:(NSString *)qName
{
    [Elements addObject:Element];
}

//对元素解析过程中，将得到的字符串存加到Element后面。因为这里只是得到元素的部分字符，所以对元素解析过程中会多次
//调用这个方法，将所有的连起来才是完整的字符串
- (void)parser:(NSXMLParser *)parser foundCharacters:(NSString *)string
{
    Element = [Element stringByAppendingString:string];
}

//对XML文档解析完毕，将相关信息显示到界面中
- (void)parserDidEndDocument:(NSXMLParser *)parser
{
    city.text = [Elements objectAtIndex:0];
    date.text = [Elements objectAtIndex:3];
    detail.text = [[[Elements objectAtIndex:4] stringByAppendingString:@"\n"] stringByAppendingString:[Elements objectAtIndex:6]];
}


- (void)viewDidLoad
{
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.
}

- (void)viewDidUnload
{
    [self setCity:nil];
    [self setDate:nil];
    [self setDetail:nil];

    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}

- (BOOL)shouldAutorotateToInterfaceOrientation:(UIInterfaceOrientation)interfaceOrientation
{
    return (interfaceOrientation == UIInterfaceOrientationPortrait);
}

- (void)dealloc {
    [city release];
    [date release];
    [detail release];

    [super dealloc];
}
@end