title: changing property contentsGravity in transform-only layer, will have no effect
body: <p>I started to create a very simple tic-tac-toe game.
  The main goal is to make the view proportional to all screen sizes of all iOS devices.
  So I put the image on a <code>ViewController</code>, make it full size of screen and then I put it into a Stack View. I've added constrains to this Stack View 0 to all sides.
  And when I ran the simulator then everything looks good. But I receive a message in console panel. What does it mean?</p>
  <p><img src="https://i.stack.imgur.com/cRAQk.jpg" alt="screenshot" /></p>