deltaY
The y-coordinate change for scroll wheel, mouse-move, mouse-drag, and swipe events.
Declaration
var deltaY: CGFloat { get }Discussion
This property is only valid for scroll wheel, mouse-move, mouse-drag, and swipe events. For swipe events, a nonzero value represents a horizontal swipe; -1.0 corresponds to swipe down and 1.0 corresponds to swipe up.
For scroll wheel events, use scrollingDeltaY instead.