title: How to correctly push to another Navigation Controller
body: <p>I have some VC which should push to <strong>ANOTHER</strong> Navigation Controller.
  If I do just</p>
  
  <pre><code>self.navigationController?.pushViewController(self.storyboard!.instantiateViewControllerWithIdentifier("someID") as someVC, animated: true)
  </code></pre>
  
  <p>this is not working. I can add </p>
  
  <pre><code>    dispatch_async(dispatch_get_main_queue()) { 
           self.navigationController?.pushViewController(self.storyboard!.instantiateViewControllerWithIdentifier("someID") as someVC, animated: true)
      }
  </code></pre>
  
  <p>So it works but as I know it's not correctly way to use it. What I should use? <code>presentViewController</code> ?</p>