成功调用后不支持的 URL 错误

Question

我很困惑为什么即使图像已成功下载并显示，错误块仍在调用。我在日志中得到的错误是，

Error = Error Domain=NSURLErrorDomain Code=-1002 "不支持的 URL" UserInfo=0x7fe7840d8000 {NSUnderlyingError=0x7fe781d5b5e0 "不支持的 URL", NSErrorFailingURLStringKey=, NSErrorFailingURLKey=, NSLocalizedDescription=不支持的 URL}

即使我收到此错误，我也可以获取图像，对其进行解析并将其显示在应用程序中。这段代码我哪里错了，

@try{
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^{
NSURL *url = [NSURL URLWithString:imageUrl];
NSURLRequest *req = [NSURLRequest requestWithURL:url];
[NSURLConnection sendAsynchronousRequest:req queue:[[NSOperationQueue alloc] init] completionHandler:^(NSURLResponse *res, NSData *data, NSError *error){
 UIImage *thumbImage = nil;
 if ([data length] >0 && error == nil){
    NSLog(@"image was downloaded.");
    thumbImage = [UIImage imageWithData:data];
 }
 else if ([data length] == 0 && error == nil){
    NSLog(@"Nothing was downloaded.");
    [loaderView removeFromSuperview];
 }
 else if (error != nil){
    NSLog(@"Error = %@", error);
    [loaderView removeFromSuperview];
 }
  dispatch_async(dispatch_get_main_queue(), ^{
    imageViewtoApply.image = thumbImage;
    [webServiceDelegate imageDownloadFinished];
    [loaderView removeFromSuperview];
    });
   }];
 });
}

Answer 1

查看http状态码，可能是错误码。

将响应投射到 NSHTTPURLResponse 并检查 statusCode 属性。

NSHTTPURLResponse *URLResponse = (NSHTTPURLResponse *)res;
NSLog(@"http status code: res.statusCode", %i);