title: How to trap the back button event
body: <p>I have a UITableViewController that launches a UIViewController and I would like to trap whenever the back button is pressed in the child controller, which is the class that derives from 'UIViewController'. I can change the Back Button title but setting the target &amp; action values when setting the backBarButtonItem seems to get ignored. What's a way to receiving some kind of notification that the Back button was tapped?</p>
  
  <pre><code>- (void)showDetailView 
  {
      // How I'm creating &amp; showing the detail controller
      MyViewController *controller = [[MyViewController alloc] initWithNibName:@"MyDetailView" bundle:nil];   
  
      UIBarButtonItem *backButton = [[UIBarButtonItem alloc] initWithTitle:@"Pages"
                              style:UIBarButtonItemStyleBordered 
                              target:self                                     
                              action:@selector(handleBack:)];
  
      self.navigationItem.backBarButtonItem = backButton;
      [backButton release];
  
      [self.navigationController pushViewController:controller animated:animated];
      [controller release];
  
  }   
  
  - (void)handleBack:(id)sender
  {
      // not reaching here
      NSLog(@"handleBack event reached");
  }
  </code></pre>