title: Swift 4 back button doesn't appear
body: <p>I have problem... i have two ViewControllers and i use this code to pass from 1st VC to 2nd</p>
  
  <pre><code>let storyBoard: UIStoryboard = UIStoryboard(name: "Main", bundle: nil)
      let newViewController = storyBoard.instantiateViewController(withIdentifier: "EVSignInViewController") as! EVSignInViewController
      self.present(newViewController, animated: true, completion: nil)
  </code></pre>
  
  <p>The problem is.. i want to display back button on 2nd VC. I already tried use Editor->Embed in-> Navigation controller on 1st VC. Also i use this</p>
  
  <pre><code>navigationController?.setNavigationBarHidden(false, animated: true)
  navigationItem.backBarButtonItem = UIBarButtonItem(title:"", style:.plain, target:nil, action:nil)
  </code></pre>