title: Custom UIBarButtonItem in UISplitViewController doesn't respond to clicks (iPhone)
body: <p>I'm trying to customize the appearance of a <code>UIBarButtonItem</code> on a <code>UISplitViewController</code> divided into two <code>UINavigationController</code>'s (the detail and master views), but keep hitting a brick wall. I first followed the advice <a href="https://stackoverflow.com/questions/25852593/uisplitviewcontroller-displaymodebuttonitem">here</a>, but have been unable to achieve the desired results.</p>
  
  <p>If if I implement the back button in the <code>viewDidLoad</code> method of my Detail View Controller in this way:</p>
  
  <pre><code>if let svc = splitViewController {
      navigationItem.leftBarButtonItem = svc.displayModeButtonItem()
  }
  </code></pre>
  
  <p>I get the default 'Back' button that navigates back to Master View controller. But if I try to customize the button using the following code:</p>
  
  <pre><code>    if let svc = splitViewController {
          let searchButton = UIBarButtonItem(
              image: UIImage(named: "magnifying-glass"),
              style: UIBarButtonItemStyle.Plain,
              target: svc.displayModeButtonItem().target,
              action: svc.displayModeButtonItem().action
          )
  
          navigationItem.leftBarButtonItem = searchButton
      }
  </code></pre>
  
  <p>I get the desired icon in the navbar but it does nothing when clicked. I've debugged the action and target in the console and for both the action is "_triggerDisplayModeAction:" and the controller is an instance of the UISplitViewController.</p>
  
  <p>Any ideas on what's going on here?</p>