Instance Method

beginTracking(_:with:)

Called when a touch event enters the control’s bounds.

Declaration

func beginTracking(_ touch: UITouch, with event: UIEvent?) -> Bool

Parameters

touch

The object containing information about the touch event.

event

The event object containing the touch event.

Return Value

true if the control should continue tracking touch events or false if it should stop. This value is used to update the isTracking property of the control.

Discussion

The default implementation of this method always returns true. Subclasses can override this method and use it to respond to events. Use the provided event information to detect which part of your control was hit and to set up any initial state information. If you want to continue tracking the touch event, return true. If you want to stop tracking the touch event, return false.

See Also

Tracking Touches and Redrawing Controls

func continueTracking(UITouch, with: UIEvent?) -> Bool

Called when a touch event associated with the control is updated.

func endTracking(UITouch?, with: UIEvent?)

Called when a touch event associated with the control ends.

func cancelTracking(with: UIEvent?)

Tells the control to cancel tracking related to the given event.

var isTracking: Bool

A Boolean value indicating whether the control is currently tracking touch events.

var isTouchInside: Bool

A Boolean value indicating whether a tracked touch event is currently inside the control’s bounds.