UIPinchGestureRecognizer Class Reference
| Inherits from | |
| Conforms to | |
| Framework | /System/Library/Frameworks/UIKit.framework |
| Availability | Available in iOS 3.2 and later. |
| Companion guide | |
| Declared in | UIPinchGestureRecognizer.h |
Overview
UIPinchGestureRecognizer is a concrete subclass of UIGestureRecognizer that looks for pinching gestures involving two touches. When the user moves the two fingers toward each other, the conventional meaning is zoom-out; when the user moves the two fingers away from each other, the conventional meaning is zoom-in.
Pinching is a continuous gesture. The gesture begins (UIGestureRecognizerStateBegan) when the two touches have moved enough to be considered a pinch gesture. The gesture changes (UIGestureRecognizerStateChanged) when a finger moves (with both fingers remaining pressed). The gesture ends (UIGestureRecognizerStateEnded) when both fingers lift from the view.
Properties
scale
The scale factor relative to the points of the two touches in screen coordinates.
Discussion
You may set the scale factor, but doing so resets the velocity.
The scale value is an absolute value that varies over time. It is not the delta value from the last time that the scale was reported. Apply the scale value to the state of the view when the gesture is first recognized—do not concatenate the value each time the handler is called.
Availability
- Available in iOS 3.2 and later.
Declared In
UIPinchGestureRecognizer.hvelocity
The velocity of the pinch in scale factor per second. (read-only)
Availability
- Available in iOS 3.2 and later.
Declared In
UIPinchGestureRecognizer.h© 2012 Apple Inc. All Rights Reserved. (Last updated: 2012-09-19)