将[NSURLConnection sendAsynchronousRequest：...]总是发送完成块？ [英] Will [NSURLConnection sendAsynchronousRequest: ...] always send completion block?

问题描述

很可能是一个相当琐碎的问题，但将完成块总是使用 [NSURLConnection sendAsynchronousRequest：...] 调用？或者我必须实现一个超时定时器吗？

Most likely a rather trivial question but will the completion block always be called using [NSURLConnection sendAsynchronousRequest: ...]? OR do I have to implement a timeout timer?

考虑下面的情况，我在呼叫之前添加 MBProgressView 仅在完成块中删除它：

Consider the following where I add a MBProgressView before the call and remove it ONLY in the completion block:

[self showHUDWithTitle:@"Configuring"];
[NSURLConnection sendAsynchronousRequest:request
                                   queue:[[NSOperationQueue alloc] init]
                       completionHandler:^(NSURLResponse *response,
                                           NSData *data,
                                           NSError *error) {

     if ([data length] >0 && error == nil) {
         [self hideHUDWithFlag:YES 
                      andTitle:@"Finished" 
                   andSubtitle:@"(Box was configured)"];

     } else if ([data length] == 0 && error == nil) {
         [self hideHUDWithFlag:NO 
                      andTitle:@"Failed" 
                   andSubtitle:@"(Check box connection)"];
         NSLog(@"Nothing was downloaded.");

     } else if (error != nil) {
        [self hideHUDWithFlag:NO 
                     andTitle:@"Error" 
                  andSubtitle:@"(Check box connection)"];
         NSLog(@"Error = %@", error);
     }
 }];

推荐答案

是的，完成处理程序总是被调用。如果请求由于超时而失败，则会设置错误，并且 data = nil 。

Yes, the completion handler is always called. If the request fails due to a timeout, the error will be set and data = nil.

A NSURLRequest 的默认超时为60秒，但您可以为 request.timeoutInverval指定不同的值，然后开始连接。

A NSURLRequest has a default timeout of 60 seconds, but you can assign a different value to request.timeoutInverval before starting the connection. So there is no need for an extra timer.

添加：在超时的情况下：

• [error domain] 是 NSURLErrorDomain 和


• [错误代码] 是 NSURLErrorTimedOut ，

• [error domain] is NSURLErrorDomain, and
• [error code] is NSURLErrorTimedOut,

如果你只是想出现错误信息，可以使用 [error localizedDescription] 时间到。在这种情况下。 （这可能取决于区域设置。）

If you just want to present an error message, you can use [error localizedDescription], which is "The request timed out." in this case. (This may depend on the locale.)

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