title: UIViewController viewDidAppear - because it was pushed or because subview was popped?
body: <p>In my app, I have about a dozen different view controllers, pushed onto or popped from the stack in different orders.  When a view has appeared (I'm using <code>viewDidAppear</code> method) I need to determine whether this is because this view has just been pushed onto the stack or because one of its subviews was popped from the stack.</p>
  
  <p>I went through this question: <a href="https://stackoverflow.com/questions/1816614/viewwilldisappear-determine-whether-view-controller-is-being-popped-or-is-showi">viewWillDisappear: Determine whether view controller is being popped or is showing a sub-view controller</a></p>
  
  <p>But I don't think it's helping me very much.  Any suggestions please?</p>