问题
I have a UIScrollView with varying numbers of items/subviews. When there is more than one item, scrolling bounce works. However, there are times when the scrollview should only have one item, and I would like to provide the feedback to the user that their scrolls are being recognized--thus the bounce effect. However, UIScrollView disables scrolling with just one item.
回答1:
Answer: set alwaysBounceHorizontal or alwaysBounceVertical to true. I answered my own question while writing this up and figured I might as well post it to help others.
回答2:
Additionally, a UIScrollView will not scroll in (width / height) if the contentSize property is not greater than the frame property (in width / height)
来源：https://stackoverflow.com/questions/5021338/force-uiscrollview-to-bounce-scrolling-even-with-a-single-item