ios - 一一调用NSURLConnection

Question

我有一个包含 10 个 URL 的 NSMutableArray，我需要从中获取 HTTP header 。

下面是我的代码:

for(int i=0; i<[contactsArray count];i++)
{
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
    NSString *reqstr=[NSString stringWithFormat:@"%@",urlString ];
    [request setURL:[NSURL URLWithString:reqstr]]; 
    NSLog(@"requested url is %@",reqstr);

    [request setHTTPMethod:@"POST"];
    [request setValue:@"application/json" forHTTPHeaderField:@"Accept"];
    [request setValue:@"application/json" forHTTPHeaderField:@"content-type"];
    [request setHTTPBody:[mDict JSONData]];

    NSURLConnection *theConnection=[[NSURLConnection alloc]initWithRequest:request         delegate:self startImmediately:YES];

}

当前 结果:所有请求都同时发送到服务器。

预期结果:想要在收到响应后发送一个请求以切断我想在后台发送另一个请求。

有什么建议吗？

Answer 1

重构您的代码以使用 sendAsynchronousRequest:queue:completionHandler: 方法，并在当前帖子完成后调用自身:

将您的计数移至实例变量。我们称它为 currentItem。您的代码可能如下所示:

- (void) postItems;
{
  while (currentItem < [contactsArray count)
  {
    NSMutableURLRequest *request = [[NSMutableURLRequest alloc] init];
    NSString *reqstr=[NSString stringWithFormat:@"%@",urlString ];
    [request setURL:[NSURL URLWithString:reqstr]]; 
    NSLog(@"requested url is %@",reqstr);

    [request setHTTPMethod:@"POST"];
    [request setValue:@"application/json" forHTTPHeaderField:@"Accept"];
    [request setValue:@"application/json" forHTTPHeaderField:@"content-type"];
    [request setHTTPBody:[mDict JSONData]];

    [NSURLConnection sendAsynchronousRequest: request 
      queue:  dispatch_get_main_queue ()
      completionHandler: ^(NSURLResponse *response, NSData *data, NSError *error)
      {
        //check for errors
        //save any response data

        //Now trigger the next request
        currentItem++
        [self postItems];
      }
    ];
  }
}

(完成 block 的语法可能不完全正确。我对带参数的 block 的语法有点纠结。)