title: Checking if a UIViewController is about to get Popped from a navigation stack?
body: <p>I need to know when my view controller is about to get popped from a nav stack so I can perform an action.</p>
  
  <p>I can't use -viewWillDisappear, because that gets called when the view controller is moved off screen for ANY reason (like a new view controller being pushed on top).</p>
  
  <p>I specifically need to know when the controller is about to be popped itself.</p>
  
  <p>Any ideas would be awesome, thanks in advance.</p>