This is an interesting idea. If one wanted to attempt a mechanism like this in iOS, what APIs would be useful? I don't know UIGestureRecognizer & friends ve

This is an interesting idea. If one wanted to attempt a mechanism like this in iOS, what APIs would be useful? I don't know UIGestureRecognizer & friends very well at all, but it looks like it wouldn't help when needing to measure contact-area at a given contact point. Any iOS programmers here that know?