title: Set subview height relative to parent view in Storyboard
body: <p>I have a <code>UIImageView</code> in a <code>UIViewController's</code> view. What I want is to set it's height <strong>1/3rd</strong> that of the view no matter what the screen size is. I of course know how to do this from code. But how to accomplish this using <strong>Storyboard/Interface builder</strong> only ?</p>