title: Detect when UIAlertController is being dismissed by another UIViewController
body: <p>Since iOS 8 and the new UIAlertController, in a scenario where: </p>
  
  <ul>
  <li>A UIAlertController is presented. </li>
  <li>A local push notification banner is displayed on top, as a UIWindow.</li>
  <li>User taps on the banner and then navigated to a different UIViewController and the UIAlertController is being dismissed by the window.rootViewController... </li>
  </ul>
  
  <p>Is there a way to detect such dismissal that is not activated by any of the UIAlertAction buttons?</p>