title: Position is ambiguous for image view
body: <p>I'm just following the tutorial from Apple, and I get an error when I set the ratio 1:1 to the image view:</p>
  
  <p><a href="https://i.stack.imgur.com/wPm8M.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/wPm8M.png" alt="enter image description here"></a></p>
  
  <p>I think it's because the tutorial is for xCode 7, so how to fix it ?</p>