title: Swift 4 iOS 11 navigation bar back button is pushed by a title view with long text
body: <p>For a long title on iOS 11, the back button arrow and text are not showing.</p>
  
  <p>I searched for a solution and the closest I got was <a href="https://stackoverflow.com/a/44456952/429763">navigation bar rightbaritem image-button bug iOS 11</a></p>
  
  <p>It looks like this<br>
  <a href="https://i.stack.imgur.com/z58QM.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/z58QM.png" alt="as it looks with a long title"></a><br>
  When it should look like this for long titles also<br>
  <a href="https://i.stack.imgur.com/yfSvp.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/yfSvp.png" alt="the back button should show as it does with a short title"></a><br>
  My problem though is that I don't have an explicit button added, instead the titleview pushes the "&lt; Back" default leftBarButtonItem that I create:</p>
  
  <p><code>navigationItem.backBarButtonItem = UIBarButtonItem(title: NSLocalizedString("Back",  comment: ""), style: .plain, target: nil, action: nil)</code></p>
  
  <p>How can I add constraints to that (UIBarButtonItem)?</p>