NSTouch
A snapshot of a particular touch at an instant in time.
Declaration
class NSTouchOverview
A touch event is not persistent throughout the touch. A touch creates new instances as it progresses. Use the identity property to follow a specific touch across its lifetime.
Touches do not have a corresponding screen location. The first touch of a touch collection latches to the view underlying the cursor using the same hit detection as mouse events. Additional touches on the same device latch to the same view. Latches remain on views until the user ends a touch or an event cancels it.