Question

Apple documentation says that scrollViewWillScrollToTop: will be called as part of the UIScrollViewDelegate protoco. However, this method doesn’t seem to exist even when I recursively grep through the /Developer folder. I don’t see where this method is being called nor its prototype. Any hints?

Answer 1

Are you referring to this?

This gesture works on a single visible scroll view; if there are
multiple scroll views (for example, a date picker) with this property
set, or if the delegate returns NO in scrollViewWillScrollToTop:,
UIScrollView ignores the request. After the scroll view scrolls to the
top of the content view, it sends the delegate a
scrollViewDidScrollToTop: message.

It’s a typo in the docs. They meant to say scrollViewShouldScrollToTop:. You can see they are mentioning returning a BOOL value, and will... delegate methods usually don’t return anything. The ones starting with should... on the other hand do.

I suggest you report this by clicking the “It’s good, but…” link in the footer of the doc. I will do the same.