title: How do I override the back navigationItem?
body: <p>In my RecordViewController, within the <code>didSelectRowAtIndexPath</code> I push a detailViewController (which inherits from <code>UIViewController</code>):</p>
  
  <pre><code>[[self navigationController] pushViewController:detailViewController animated:YES];
  </code></pre>
  
  <p>Once the DetailViewController appears I can see a <code>Back</code> navigationButton in the top left corner, which automatically pops the current view controller to get back to the previous ViewController.</p>
  
  <p>Now I need to show a <code>UIAlertView</code> and ask the user, if the data should be saved or not.</p>
  
  <p>And only when the user has made a decision, the current view controller should disappear.</p>
  
  <p>My problem is if I put this code into <code>viewWillDisappear</code>, it is already too late.  I can't stop the process while showing the <code>UIAlertView</code>. This needs to be intercepted the moment the user pressed the back button.</p>
  
  <p>Is there a method I could override to achieve this?</p>