swipe event (delta 0 0, phase 'maybegin')
scroll event (delta 1 0, phase 'began')
scroll event (delta 1 0, phase 'changed')
didBeginSwipe
swipe event (delta 1 0, phase 'changed')
swipe event (delta 256 0, phase 'changed')
swipe event (delta 0 0, phase 'ended')
willEndSwipe
didEndSwipe
didRemoveSwipeSnapshot