title: iOS 11 black bar appears on navigation bar when pushing view controller
body: <p>I have this weird bug only in iOS 11, in lower iOS, everything works fine.
  The problem is that whenever pushing to a view controller, there is a black space appears on top of the navigation bar. Has anyone else experienced this problem and how to fix it?</p>
  
  <p><a href="https://i.stack.imgur.com/1MFU1.png" rel="noreferrer"><img src="https://i.stack.imgur.com/1MFU1.png" alt="Pushing "></a></p>