title: iOS full screen background image for all screen sizes
body: <p>I'm trying to set a background image for my app that will scale to fill the 4, 4.7, and 5.5 inch screens.  </p>
  
  <ul>
  <li>I'm working in XCode 6 with swift</li>
  <li>I created a 640 x 1136 image, and pasted @1x, @2x, and @3x images in my images.xcasetts folder. I selected the 'scale to fill' mode for the image view.</li>
  <li>I created a UIImage in the main.storyboard file for the 4 inch screen.  This image fills the screen just fine when I build.</li>
  <li>I think I've tried just about every combination of height / width / aspect ratio constraints with no luck.</li>
  </ul>