I heard that UISwipeGestureRecognizer can be used to distinguish between a slow swipe and a fast flick. But I can't find any API to tell the difference.
Do you specifically need to use UISwipeGestureRecognizer, or can you use UIPanGestureRecognizer instead? UIPanGestureRecognizer gives you precise movement data whereas UISwipeGestureRecognizer is more basic and just detects whether or not a swipe happened (and in which direction).
UIPanGestureRecognizer has a -velocityInView: method which returns a CGPoint, expressing points per second, vertically and horizontally.