title: UIAlertController not displaying Alert in iOS 8.4.1
body: <p>I have presented view controller using </p>
  
  <pre><code>[self presentViewController:viewController animated:YES completion:nil];
  </code></pre>
  
  <p>In the presented view controller I am trying to present UIAlertcontroller, it is not presenting also showing warning in the console in iOS 8.4.1</p>
  
  <pre><code>dispatch_async(dispatch_get_main_queue(), ^{
      UIAlertAction *extend_action = nil;
      UIAlertAction *ok_action  = nil;
  
      UIAlertController *controller = [UIAlertController alertControllerWithTitle:@"Call will begin"
                                                                          message:msg_str   
                                                                   preferredStyle:UIAlertControllerStyleAlert];
  
      extend_action = [UIAlertAction  actionWithTitle:@"Extend Time?" 
                                                style:UIAlertActionStyleDefault
                                              handler:^(UIAlertAction *action) { 
                                                   // Method.
                                              }];
      ok_action = [UIAlertAction actionWithTitle:@"Ok" 
                                           style:UIAlertActionStyleDefault                            
                                         handler:^(UIAlertAction *action) { 
                                      }];                        
      [controller addAction:extend_action];
      [controller addAction:ok_action];
      [self presentViewController:controller animated:YES completion:nil];
  });
  </code></pre>
  
  <p>Attempt to present UIAlertController on  whose view is not in the window hierarchy! 
  I am getting above warning.</p>