title: UIAlertController is covered by a view on window
body: <p>When I add a UIView to keyWindow,the alertController is covered by the view.Here is the code.</p>
  
  <pre><code>- (void)touch {
      UIWindow *currentWindow = [UIApplication sharedApplication].keyWindow;
      UIView *viewhaha = [[UIView alloc] initWithFrame:[UIScreen mainScreen].bounds];
      viewhaha.backgroundColor = [UIColor redColor];
      [currentWindow addSubview:viewhaha];
  
      UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"123" message:@"123" preferredStyle:UIAlertControllerStyleAlert];
      UIAlertAction *action1 = [UIAlertAction actionWithTitle:@"123" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {
      }];
  
      [alertController addAction:action1];
      [self presentViewController:alertController animated:YES completion:^{
      }];
  }    
  </code></pre>
  
  <p>and here is the Image.
  <a href="https://i.stack.imgur.com/XyKVM.png" rel="nofollow noreferrer">Image</a></p>
  
  <p>Do you know how to resolve it?</p>