super: UIScrollView on iOS
This class is reserved and cannot be directly instantiated.
DidScroll() This event is called when the user scrolls the content view.
DidEndDragging(decelerate: Bool) This event is called when dragging ended in the scroll view. The scroll view sends this event when the user’s finger touches up after dragging content. The decelerating property of the scroll view controls deceleration. The decelerate value is true if the scrolling movement will continue, but decelerate, after a touch-up gesture during a dragging operation. If the value is NO, scrolling stops immediately upon touch-up.
DidEndDecelerating() This event is called when the scroll view ends decelerating the scrolling movement.