title: Set Autolayout Constraints Relative to Device Size
body: <p>I fell into the trap of relying on Autolayout. I currently have a ViewController with a ton of UIViews and realized they're distorted on smaller devices (iPhone 4s and 5).</p>
  
  <p>Is it possible to set constraints in Autolayout relative to device size.</p>
  
  <p><strong>For example, I have one <code>UIView</code> with several other <code>UIViews</code> aligned edges. I would like to change the height in Autolayout of that one UIView to equal half the device height.</strong></p>