I use pure structure like the following
-view
-scrollView
-view A
-view B
-Button
Make sure Button(THE LAST view) has a constraint(vertical spacing from its bottom to superview, which is the scrollview), in this case, no matter what changes for your view A and view B would be, scrollView’s height will be changed accordingly.
I reference to this great online book site.
Just read the “Creating a scroll view” section, you should have an idea.
I had the similar problem that I was creating a detail view and using Interface Builder with Auto layout is such a good fit for the task!
Good luck!
(Additional resources:
Stack overflow discussion about the auto layout for scroll view.
iOS 6 has a Release Notes talking about Auto Layout support for UIScrollView.
Free online iOS book explanation about scroll view. This actually helped me a lot!