1.NSMutableURLRequest

NSMutableURLRequest是NSURLRequest的子类，常用方法

//设置请求超时等待时间（超过这个时间就算超时，请求失败）
- (void)setTimeoutInterval:(NSTimeInterval)seconds;

//设置请求方法（比如GET和POST）
- (void)setHTTPMethod:(NSString *)method;

//设置请求体
- (void)setHTTPBody:(NSData *)data;

//设置请求头
- (void)setValue:(NSString *)value forHTTPHeaderField:(NSString *)field;

//创建GET请求
NSString *urlStr = [@"http://www.jianshu.com/users/468d1f0192cb/latest_articles" stringByAddingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
NSURL *url = [NSURL URLWithString:urlStr];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];

//创建POST请求
NSString *urlStr = @"http://www.jianshu.com/users/468d1f0192cb/latest_articles";
NSURL *url = [NSURL URLWithString:urlStr];
NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
request.HTTPMethod = @"POST";
// 请求体
NSString *bodyStr = @"username=solozyx&pwd=solozyx";
request.HTTPBody = [bodyStr dataUsingEncoding:NSUTF8StringEncoding];

demo:

- (void)post {
    // 1.请求路径
    NSURL *url = [NSURL URLWithString:@"http://www.jianshu.com/users/468d1f0192cb/latest_articles"];
    // 2.创建请求
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
    // 更改请求方法
    request.HTTPMethod = @"POST";
    // 设置请求体
    request.HTTPBody = [@"username=solozyx&pwd=solozyx" dataUsingEncoding:NSUTF8StringEncoding];
    // 设置超时(5秒后超时)
    request.timeoutInterval = 5;
    // 设置请求头
    [request setValue:@"iOS 9.0+" forHTTPHeaderField:@"User-Agent"];
    
    // 3.发送请求
    [NSURLConnection sendAsynchronousRequest:request
                                       queue:[[NSOperationQueue alloc] init]
                           completionHandler:^(NSURLResponse *response, NSData *data, NSError *connectionError) {
                               if (connectionError) { // 比如请求超时
                                   NSLog(@"请求失败");
                               } else {
                                   // 把得到的页面显示在webView
                                   [[NSOperationQueue mainQueue] addOperationWithBlock:^{
                                       NSString *htmlStr = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
                                       NSLog(@"webView Code : %@",htmlStr);
                                   }];
                               }
                           }];
}