How to disable horizontal scrolling of UIScrollView?

You have to set the contentSize property of the UIScrollView. For example, if your UIScrollView is 320 pixels wide (the width of the screen), then you could do this:

CGSize scrollableSize = CGSizeMake(320, myScrollableHeight);
[myScrollView setContentSize:scrollableSize];

The UIScrollView will then only scroll vertically, because it can already display everything horizontally.