Limiting the scrollable area in UIScrollView

Question

I have a UIScrollView that is scrolling a fairly large UIView.

At certain times I want to limit the area the user can scroll around in. For example, I may only want to allow them to view the bottom quarter of the view.

I am able to limit the area by overriding scrollViewDidScroll and then calling setContentOffset if the view has scrolled too far. But this way I can't get it bounce back as smoothly as the UIScrollView can naturally do when scrolling beyond the bounds of the UIView.

Is there a better way to limit the scrollable area in a UIScrollView?

Answer 1

I would change the contentSize property of the scroll view to the size of the area you want the user to be able to scroll around in and adjust the frame.origin of the subview such the upper left boundary you want appears at (0, 0) relative to the scroll view. For example, if your view is 800 points tall and you want to show the bottom quarter, set the height of contentSize to 200 and set the y component of view.frame.origin to -600.