Dev:UIGestureRecognizer

UIGestureRecognizer is an abstract class that provides an object-oriented way to add actions to different gestures. It has been a documented class since firmware 3.2. See also: SBGestureRecognizer.

The typical code that adds a gesture recognizer is

UITapGestureRecognizer
UITapGestureRecognizer represents the gesture that p fingers tapped the screen q times consecutively.
 * Input properties: numberOfTaps (q), numberOfFingers (p)
 * Output properties: location, touches

UIPinchGestureRecognizer
UIPinchGestureRecognizer represents the gesture that 2 fingers moving towards or away from a center point. This gesture is usually used for scaling a view.
 * Input properties: scaleThreshold
 * Output properties: scale, velocity, anchorPoint, transform

scaleThreshold is the critical scale the fingers must first move apart/together before this recognizer could fire.

UILongPressGestureRecognizer
UILongPressGestureRecognizer represents the gesture that p fingers moved/stayed on the screen continuously for T seconds. Optionally, numberOfTapsRequired may be specified to require a tap-tap/hold pattern.


 * Input properties: numberOfTapsRequired, numberOfFingers (p), delay (T), allowableMovement
 * Output properties: touches, centroid, startPoint

UIDragRecognizer
UIDragRecognizer represents the gesture that 1 or more fingers moving on the screen for a distance of d. Optionally it may also be constrained to moving only within an angle of &theta; ± &Delta;&theta;.


 * Input properties: minimumDistance (d), angle (&theta;), maximumDeviation (&Delta;&theta;), restrictsToAngle
 * Output properties: touch, startPosition, startAngle

Note that the angles are in radians.

UIPanGestureRecognizer
UIPanGestureRecognizer represents the gesture that 1 or more fingers moving on the screen for a relatively large distance. This gesture is usually used for scrolling, and is used by UIScroller and UIScrollView.


 * Input properties: directionalLockEnabled
 * Output properties: offset, velocity, transform

UITapAndAHalfRecognizer
UITapAndAHalfRecognizer represents the gesture that 1 finger tapped the screen q times consecutively, and then moved/stayed on the screen.


 * Input properties: numberOfFullTaps (q), allowableMovement
 * Output properties: touch

Note: UITapAndAHalfRecognizer is a private, undocumented class. UILongPressGestureRecognizer should be used instead; UITapAndAHalfRecognizer's numberOfFullTaps requires is equivalent to UILongPressGestureRecognizer's numberOfTapsRequired.

UIRotationGestureRecognizer
UIRotationGestureRecognizer TODO


 * Output properties: rotation, velocity

UISwipeGestureRecognizer

 * TODO.

Custom Gesture Recognizers

 * TODO.