title: iOS 7 UINavigationBar show default back button without title
body: <p>I have a <code>UINavigationController</code> with <code>rootViewController</code> as my custom <code>SearchViewController</code> and inside that I'm pushing a <code>detailViewController</code>.</p>
  
  <p>When I push <code>detailViewController</code> the back button shows a back arrow and the title of the previous <code>viewController</code>.</p>
  
  <p>I want the title to be hidden and only the back arrow should be shown.</p>
  
  <p>Whenever I set <code>self.title = @"";</code> before pushing, it works but when come back I have to reset the title back in <code>viewWillAppear</code>. But this is creating some other problems and causing inconsistancy because the title of the first view controller is not constant.</p>
  
  <p>Any help would be appreciated.</p>