title: When/why/how to use the UINavigationControllerDelegate Protocol Instance Methods?
body: <p>When/why/how would you use these methods?</p>
  
  <pre><code>- navigationController:willShowViewController:animated:
  – navigationController:didShowViewController:animated:
  </code></pre>
  
  <p>Can't you just use these UIViewController Instance Methods instead?</p>
  
  <pre><code>– viewWillAppear:
  – viewDidAppear:
  – viewWillDisappear:
  – viewDidDisappear:
  </code></pre>