title: iOS 6 deprecation of viewWillUnload & move to didReceiveMemoryWarning
body: <p>I'm  new developer about to launch my first app. I'm confused about the deprecation of <code>viewDidUnload</code> as described below in Apple's iOS 6 release notes:</p>
  
  <blockquote>
    <p>In iOS 6, the viewWillUnload and viewDidUnload methods of
    UIViewController are now deprecated. If you were using these methods
    to release data, use the didReceiveMemoryWarning method instead. You
    can also use this method to release references to the view
    controller’s view if it is not being used. You would need to test that
    the view is not in a window before doing this.</p>
  </blockquote>
  
  <p>Why is this happening? What guidelines should I follow to ensure that this change doesn't cause any performance issues in my app? </p>
  
  <p>Thanks.</p>