POST請求和GET請求相像
0.首先得有一個NSURL，告訴請求路徑。此時POST請求的請求參數(shù)不是放請求路徑（放在請求體里）

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
{
    //1.請求路徑
    NSURL * url = [NSURL URLWithString:@"http://120.25.226.186:32812/login"];
    //2.創(chuàng)建請求對象
    NSMutableURLRequest *requset = [NSMutableURLRequest requestWithURL:url];
    //告知是GET請求還是POST請求
    //更改請求方法,不寫的話就是GET
    requset.HTTPMethod = @"POST";
    //設(shè)置請求體
    requset.HTTPBody = [@"username=520it&pwd=520it" dataUsingEncoding:NSUTF8StringEncoding];
    //設(shè)置超時（5秒后超時）只有用NSMutableURLRequest才行
    requset.timeoutInterval = 5;
    //設(shè)置請求頭
//    [requset setValue:@"iOS 9.0" forHTTPHeaderField:@"User-Agent"];
    //3.發(fā)送請求
    [NSURLConnection sendAsynchronousRequest:requset queue:[NSOperationQueue mainQueue] completionHandler:^(NSURLResponse * _Nullable response, NSData * _Nullable data, NSError * _Nullable connectionError) {
        if (connectionError) {//比如請求超時
            NSLog(@"----請求失敗");
        }else{
            NSLog(@"----%@",[[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding]);
        }        
    }];
}

NSMutableURLRequest
》設(shè)置請求超時等待時間（超過這個時間，請求失敗）
timeoutInterval/setTimeoutInterval
》設(shè)置請求體
HTTPBody/setHTTPBody
》設(shè)置請求頭
setValue:value forHTTPHeaderField:

創(chuàng)建GET和POST請求

創(chuàng)建GET請求

請求路徑 -> 轉(zhuǎn)成 url -> NSURLRequest
默認(rèn)就是GET請求

NSURL * url = [NSURL URLWithString:@"http://120.25.226.186:32812/login?username=123&pwd=123"];
NSURLRequest * request = [NSURLRequest requestWithURL:url];
[NSURLConnection sendAsynchronousRequest:request queue:...];

創(chuàng)建POST請求

url -> requset ->改成POST ->請求體

NSURL * url = [NSURL URLWithString:@"http://120.25.226.186:32812/login"];
 NSMutableURLRequest *requset = [NSMutableURLRequest requestWithURL:url];
 requset.HTTPMethod = @"POST";
requset.HTTPBody = [@"username=520it&pwd=520it" dataUsingEncoding:NSUTF8StringEncoding];
[NSURLConnection sendAsynchronousRequest:...];

兩者區(qū)別比較的大的地方就在請求參數(shù)