title: Get back parentViewController
body: <p>I have a <code>PhoneViewController : UIViewController</code></p>
  
  <pre><code>let phonePage = storyboard.instantiateViewControllerWithIdentifier("phoneViewController") as! PhoneViewController
  </code></pre>
  
  <p>I am presenting it from 2 different controllers.</p>
  
  <pre><code>// UIViewController1
  self.navigationController?.pushViewController(phonePage, animated: true)
  
  // UIViewController2
  self.presentViewController(phonePage.embedInNavController(), animated: true, completion: nil)
  </code></pre>
  
  <p>I would like to have a have to detect which controller was its parent. How would I be able to do that?</p>