title: PushViewController doesn't work - deinit called
body: <p>From firstController,I try to switch viewController :</p>
  
  <pre><code>let player = self.storyboard?.instantiateViewControllerWithIdentifier("WK_player") as? WKViewController
  self.navigationController?.pushViewController(player!, animated: true)
  </code></pre>
  
  <p>But WKViewController doesn't appears and directly call his deinit.</p>
  
  <p>It's work well with</p>
  
  <pre><code>performSegueWithIdentifier("WK_Play", sender: nil)
  </code></pre>
  
  <p>But with this, dealloc is never get called when I close player and keep existing in memory.</p>
  
  <pre><code>dismissViewControllerAnimated(true, completion: nil)
  </code></pre>
  
  <p>What is the problem ?</p>