title: add UIImageView that covers navigation bar
body: <p>I think I'm missing something simple here. I need to create a semi-transparent UIImageView that covers the entire screen including the navigation toolbar. How do I do this?</p>
  
  <p>This is what I'm trying to do ...</p>
  
  <p><img src="https://i.stack.imgur.com/CHaNZ.png" alt="enter image description here"></p>