UIKit中包含了UIGestureRecognizer类，用于检测发生在设备中的手势。UIGestureRecognizer是一个抽象类，定义了所有手势的基本行为，它有下面一些子类用于处理具体的手势：
1、拍击UITapGestureRecognizer (任意次数的拍击)
2、向里或向外捏UIPinchGestureRecognizer (用于缩放)
3、摇动或者拖拽UIPanGestureRecognizer
4、滑动UISwipeGestureRecognizer (以任意方向)
5、旋转UIRotationGestureRecognizer (手指朝相反方向移动)
6、长按UILongPressGestureRecognizer
对于不同类型的手势识别器，具有不同的配置属性。比如UITapGestureRecognizer，可以配置拍击次数。界面接收到手势之后，可以发送一 个消息，用于处理响应手势动作后的任务。当然，不同的手势识别器，发送的消息方法也会有所不同。下面列举几个具体示例代码：
一个手指，拍击两次手势
// 创建一个手势识别器 UITapGestureRecognizer *oneFingerTwoTaps = [[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(oneFingerTwoTaps)] autorelease]; // Set required taps and number of touches [oneFingerTwoTaps setNumberOfTapsRequired:2]; [oneFingerTwoTaps setNumberOfTouchesRequired:1]; // Add the gesture to the view [[self view] addGestureRecognizer:oneFingerTwoTaps]; 消息方法oneFingerTwoTaps - (void)oneFingerTwoTaps { NSLog(@"Action: One finger, two taps"); }
两个手指，拍击两次手势
UITapGestureRecognizer *twoFingersTwoTaps = [[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(twoFingersTwoTaps)] autorelease]; [twoFingersTwoTaps setNumberOfTapsRequired:2]; [twoFingersTwoTaps setNumberOfTouchesRequired:2]; [[self view] addGestureRecognizer:twoFingersTwoTaps]; 消息方法twoFingersTwoTaps - (void)twoFingersTwoTaps { NSLog(@"Action: Two fingers, two taps"); }
一个手指向上、向下滑动手势
// 向上滑动 UISwipeGestureRecognizer *oneFingerSwipeUp = [[[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(oneFingerSwipeUp:)] autorelease]; [oneFingerSwipeUp setDirection:UISwipeGestureRecognizerDirectionUp]; [[self view] addGestureRecognizer:oneFingerSwipeUp]; - (void)oneFingerSwipeUp:(UISwipeGestureRecognizer *)recognizer { CGPoint point = [recognizer locationInView:[self view]]; NSLog(@"Swipe up - start location: %f,%f", point.x, point.y); } // 向下滑动 UISwipeGestureRecognizer *oneFingerSwipeDown = [[[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(oneFingerSwipeDown:)] autorelease]; [oneFingerSwipeDown setDirection:UISwipeGestureRecognizerDirectionDown]; [[self view] addGestureRecognizer:oneFingerSwipeDown]; - (void)oneFingerSwipeDown:(UISwipeGestureRecognizer *)recognizer { CGPoint point = [recognizer locationInView:[self view]]; NSLog(@"Swipe down - start location: %f,%f", point.x, point.y); }
旋转手势
UIRotationGestureRecognizer *twoFingersRotate = [[[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(twoFingersRotate:)] autorelease]; [[self view] addGestureRecognizer:twoFingersRotate]; - (void)twoFingersRotate:(UIRotationGestureRecognizer *)recognizer { // Convert the radian value to show the degree of rotation NSLog(@"Rotation in degrees since last change: %f", [recognizer rotation] * (180 / M_PI)); }
向里或向外捏的手势
UIPinchGestureRecognizer *twoFingerPinch = [[[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(twoFingerPinch:)] autorelease]; [[self view] addGestureRecognizer:twoFingerPinch]; - (void)twoFingerPinch:(UIPinchGestureRecognizer *)recognizer { NSLog(@"Pinch scale: %f", recognizer.scale); }
UITapGestureRecognizer *twoFingersTwoTaps = [[[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(twoFingersTwoTaps)] autorelease]; [twoFingersTwoTaps setNumberOfTapsRequired:2]; [twoFingersTwoTaps setNumberOfTouchesRequired:2]; [[self view] addGestureRecognizer:twoFingersTwoTaps]; 消息方法twoFingersTwoTaps - (void)twoFingersTwoTaps { NSLog(@"Action: Two fingers, two taps"); }
