title: UIAlertController not showing from AppDelegate
body: <p>I am trying to present an <code>UIAlertController</code> globally (from a place which is not a view controller) like this but my alert does not show up. I am testing my initial alert which is shown by reachability test in App Delegate after detecting no network. I can see launch image on my screen but alert does not show up. If I use <code>UIAlertView</code>, everything looks good.</p>
  
  <p>If you had encountered similar issue then please advise.</p>
  
  <pre><code>UIAlertController *alert = [UIAlertController alertControllerWithTitle:iTitle message:iMessage preferredStyle:UIAlertControllerStyleAlert];
  id rootViewController = [UIApplication sharedApplication].delegate.window.rootViewController;
  
  if ([rootViewController isKindOfClass:[UINavigationController class]]) {
     rootViewController = [((UINavigationController *)rootViewController).viewControllers objectAtIndex:0];
  }
  
  dispatch_async(dispatch_get_main_queue(), ^{
      [rootViewController presentViewController:alert animated:YES completion:^{
          [aBlockSelf alertPresented];
      }];
  });
  </code></pre>
  
  <p><strong>EDIT:</strong></p>
  
  <p><strong>Why am I showing it from <code>AppDelegate</code>?</strong> </p>
  
  <p>As I said, I am showing an alert to user as soon as I execute my reachability test. This test has to be performed from within <code>AppDelegate</code> even before I load any view controller. So, I show a splash screen on my <code>UIWindow</code> and I am expecting my alert to come on top of it.</p>
  
  <p><strong>Is my window set up correctly when I present the alert?</strong></p>
  
  <p>Yes, I am ensuring that I present alert controller post window is correctly set and that after below lines are executed! </p>
  
  <pre><code>[self.window addSubview:self.rootViewController.view];
  [self.window makeKeyAndVisible];
  </code></pre>