title: backBarButtonItem not getting displayed
body: <p>I know <code>viewcontroller's</code> navigation item's <code>backBarButtonItem</code> gets displayed when another view controller is pushed on stack and this is 2nd <code>viewcontroller</code> from top.</p>
  
  <p>I have viewcontroller A which have following in <code>viewDidLoad</code></p>
  
  <pre><code>{
   [super viewDidLoad];
   self.navigationController.navigationBarHidden = NO;
   [self.navigationItem setBackBarButtonItem:[UIBarButtonItem itemWithImageNamed:@"ic_header_slide" selectedImage:nil target:nil action:nil]];
  }
  </code></pre>
  
  <p>When I push <code>viewcontroller B</code>, this custom back button is not getting displayed, instead I see default back button which iOS creates.</p>
  
  <p>A extends <code>UITableViewController</code> and B extends <code>UIViewController</code>. I am not setting <code>leftBarButtonItem</code>, <code>leftBarButtonItems</code>, <code>rightBarButtonItem</code>, <code>rightBarButtonItems</code> in any of these navigationItem.</p>
  
  <p>EDIT
  I have read about setting leftBarButtonItems. setting leftbarbuttonitems on B works. but I think setting backBarButtonItem on A is correct way of doing that. It is also mentioned in documentation but not working in my case. I want to ask whether there is bug in backBarButtonItem or I have some misunderstanding the way it works and I am not doing it correctly.</p>