UI2_同步下载

//
//  ViewController.m
//  UI2_同步下载
//
//  Created by zhangxueming on 15/7/17.
//  Copyright (c) 2015年 zhangxueming. All rights reserved.
//
 
#import "ViewController.h"
 
//http://iappfree.candou.com:8080/free/applications/limited?currency=rmb&page=页数
 
@interface ViewController ()
{
    NSURLConnection *_urlConnection;//苹果官方提供的, 给客户端与服务器建立连接
    NSMutableArray *_dataArray;    //提供数据
}
@end
 
//同步下载:当向服务器,发送网络请求后, 请求数据期间, UI不能交互,只有在服务器返回数据之后才能进行后续的操作
//请求的数据量比较小,特殊要求
 
@implementation ViewController
 
- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view, typically from a nib.
    [self loadDataWithPage:4];
}
 
- (void)loadDataWithPage:(NSInteger)page
{
    //创建URL对象
    NSString *urlString = [NSString stringWithFormat:@"http://iappfree.candou.com:8080/free/applications/limited?currency=rmb&page=%ld", page];
    NSURL *url = [NSURL URLWithString:urlString];
    //创建数据请求对象
    //cachePolicy 缓存协议是个枚举类型：
    //NSURLRequestUseProtocolCachePolicy 基础策略
    //NSURLRequestReloadIgnoringLocalCacheData 忽略本地缓存
    //NSURLRequestReturnCacheDataElseLoad 首先使用缓存，如果没有本地缓存，才从原地址下载
    //NSURLRequestReturnCacheDataDontLoad 使用本地缓存，从不下载，如果本地没有缓存，则请求失败。此策略多用于离线操作
    //NSURLRequestReloadIgnoringLocalAndRemoteCacheData 无视任何的缓存策略，无论是本地还是远程，总是从原地址重新下载
    //NSURLRequestReloadRevalidatingCacheData 如果本地缓存是有效的则不下载。其他任何情况都从原地址重新下载
    NSURLRequest *request = [NSURLRequest requestWithURL:url cachePolicy:NSURLRequestUseProtocolCachePolicy timeoutInterval:10];
    //状态响应
    //404(请求失败)  200(请求成功) 400(客户端语法错误) 500(服务端错误)
    NSHTTPURLResponse *response= nil;
    NSError *error = nil;
    NSData *data = [NSURLConnection sendSynchronousRequest:request returningResponse:&response error:&error];
     
    //打印状态码
    NSLog(@"%@", response);
    NSLog(@"code = %li", response.statusCode);
    NSLog(@"header = %@",response.allHeaderFields);
     
    id result = [NSJSONSerialization JSONObjectWithData:data options:NSJSONReadingMutableContainers error:nil];
     
    NSLog(@"result= %@", result);
}
 
- (void)didReceiveMemoryWarning {
    [super didReceiveMemoryWarning];
    // Dispose of any resources that can be recreated.
}
 
@end