title: Swift 4 push is not working in Storyboards
body: <p>I am trying to push a VC to different VC. Till this date, I have worked a lot with <code>.xib</code> files. So, now moving to storyboard I am facing a little problem. I have two storyboards <code>A.storyboard</code> and <code>B.storyboard</code></p>
  
  <p>What I have tried is this: </p>
  
  <pre><code>let storyBoard: UIStoryboard = UIStoryboard(name: storyboard, bundle: nil)
  
  let newViewController = storyBoard.instantiateViewController(withIdentifier: storyboardId) 
  
  controller.present(newViewController, animated: true, completion: nil)
  </code></pre>
  
  <p>This works fine for me, but I am worried about memory leakage. The other way which I know and prefer is this: </p>
  
  <pre><code>self.navigationController?.pushViewController(LoginController(), animated: true)
  </code></pre>
  
  <p>But, when I use this ^ I get a black screen and nothing. Why the push is not working here, but works fine for me in <code>.xibs</code>?</p>