title: Black screen when creating UITabBarController from xib
body: <p>I try to create <code>UITabBarController</code> from xib. So I setup tab items in xib, connect classes and xibs names for controllers like that. <a href="https://i.stack.imgur.com/YH5c4.png" rel="nofollow noreferrer">Open image in full resolution</a>.</p>
  
  <p><img src="https://i.stack.imgur.com/YH5c4.png" alt="like that"></p>
  
  <p>Then I set TabBarController as root view controller.</p>
  
  <p><img src="https://i.stack.imgur.com/0ESxz.png" alt="root view controller"> </p>
  
  <p>As result, I get a black screen with no tab items.</p>
  
  <p><img src="https://i.stack.imgur.com/sFTvV.png" alt="black screen"></p>
  
  <p>I can create <code>UITabBarController</code> programmatically, so the question is: how can I get what I create in xib?</p>