Many iOS apps have a "scroll up to refresh" feature, such as the Twitter app. If you scroll up beyond the beginning of the page or table, you'll get a message explaining how to use the feature.
That controller is not from Apple but many apps seem to use it. I was told it was released for public use by a programmer, but I can't find it after a long google session.
I'd be grateful if anyone can direct me to it! Thanks!
Here's a link to the original code by enormego on github:
This is a popular implementation: https://github.com/enormego/EGOTableViewPullRefresh
https://github.com/enormego/EGOTableViewPullRefresh
Also it was in Facebook's three20 library I guess.
I was able to find two examples a few minutes after posting this question:
来源：https://stackoverflow.com/questions/4247166/ios-scroll-up-to-refresh