title: Navigation bar height as in iMessage (iOS 10)
body: <p>How do I make the increase of the navigation bar height in iMessage (iOS 10), with animation, and when this controller is hidden, then also with the animation return the previous height?</p>
  
  <p>I read several articles, I can share them here, but they do not give such an effect as in iMessage (iOS 10). Thank you.</p>
  
  <p><strong>Update:</strong> Or how to track that the <code>UIViewController</code> is hiding on the point to make a smooth animation, since we get a <code>viewWillDisappear</code> call that the controller starts hiding, but it also may be that the user hides it with a slow gesture and therefore it is necessary to reduce the <code>NavigationBar</code> height relative to the percentage of how much the current controller already hidden. How is it better to implement it?</p>