I have a UIViewController subclass as a scene in the storyboard that contains a UIScrollView containing various subviews. One of the subviews is a
UIViewController
UIScrollView
Unfortunately, Peter and MacMark's suggestions did not work for me (Xcode 5 w/ auto-layout). The solution was to go to the storyboard, select the view controller, and Reset to Suggested Constraints in View Controller.
Reset to Suggested Constraints in View Controller