ios - 警报 View 不工作

Question

我有一个按钮，该按钮向网络服务发送调用并返回一些值。我想显示一个没有按钮的警告框，直到值从 web 服务返回。但是 alertWait 在收到值后显示。我尝试使用设置警报功能并从按钮的开头调用，但它也显示在接收值的末尾。我哪里出错了这是我的代码。

    - (IBAction)UploadButton:(id)sender
    {
      // Initializtion of some elements

        UIAlertView *alertWait;

        alertWait = [[UIAlertView alloc] initWithTitle:@"Please Wait..."
                                            message:nil delegate:self cancelButtonTitle:nil otherButtonTitles: nil];

        [alertWait show];


       //Web service call statements


        if ([status intValue] == 0) 
      {
            NSLog(@"It is zero");
            [alertWait dismissWithClickedButtonIndex:0 animated:YES];
            UIAlertView *alert =[ [UIAlertView alloc]initWithTitle:@"Success" message:@"You have successfully uploded the document and waiting for approval" delegate:self cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil];
            [alert show];
        }

   }

Answer 1

将服务调用放在后台线程上，就像下面更改的示例代码一样:

- (IBAction)UploadButton:(id)sender
{
          // Initializtion of some elements
            UIAlertView *alertWait;

            alertWait = [[UIAlertView alloc] initWithTitle:@"Please Wait..." message:nil delegate:self cancelButtonTitle:nil otherButtonTitles: nil];

            [alertWait show];

    dispatch_async(dispatch_get_global_queue( DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{

            //Web service call statements

           dispatch_async(dispatch_get_main_queue(), ^{
                //Do your UI operations here
                if ([status intValue] == 0) 
                {       
                    NSLog(@"It is zero");
                    [alertWait dismissWithClickedButtonIndex:0 animated:YES];
                    UIAlertView *alert =[ [UIAlertView alloc]initWithTitle:@"Success" message:@"You have 
successfully uploded the document and waiting for approval" delegate:self 
cancelButtonTitle:@"Ok" otherButtonTitles:nil, nil];
                    [alert show];
                }
            });
       });

}