This would give you a scroll view that resized as the view controller's view resized (such as on device rotation), and the image view would be a scrolling subview.

ENGADGET: Apple seeds iOS 6 beta 4 to developers: here's the changelog

Note that you can make a subview of the scroll view appear to float (not scroll) over the other scrolling content by creating constraints between the view and a view outside the scroll view's subtree, such as the scroll view's superview.

ENGADGET: Apple seeds iOS 6 beta 4 to developers: here's the changelog