title: Navigation bar issue in iOS11
body: <p>I was working perfectly with navigation bars iOS 10 and below previously. But now when moving to the iOS 11, It's bit weird with the navigation bar. The entire navigation bar is going up with all the navigation items. Here I've attached a screenshot of the current behavior. </p>
  
  <p><a href="https://i.stack.imgur.com/nqRRE.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/nqRRE.png" alt="enter image description here"></a></p>
  
  <p>Is this relate to constraints? And I don't need to user large titles in my application. As I think this is a matter with large titles. I've added the following code, in order to disable the large titles.</p>
  
  <pre><code>if (@available(iOS 11.0, *)) {
      [[self navigationController] navigationBar].prefersLargeTitles = NO;
      [[self navigationController] navigationItem].largeTitleDisplayMode = UINavigationItemLargeTitleDisplayModeNever;
  }
  </code></pre>
  
  <p>How may I fix this issue?</p>