UIGestureRecognizer是一个抽象类，定义了所有手势的基本行为，它有6个子类处理具体的手势：
1.UITapGestureRecognizer （任意手指任意次数的点击）
// 点击次数
numberOfTapsRequired
// 手指个数
numberOfTouchesRequired
UITapGestureRecognizer *tapGestureRecognizer = [[UITapGestureRecognizer alloc] init];
[tapGestureRecognizer addTarget:self action:@selector(gestureRecognizerHandle:)];
[tapGestureRecognizer setNumberOfTapsRequired:2];
[tapGestureRecognizer setNumberOfTouchesRequired:2];
[self.view addGestureRecognizer:tapGestureRecognizer];
2.UIPinchGestureRecognizer （两个手指捏合动作）
// 手指捏合，大于1表示两个手指之间的距离变大，小于1表示两个手指之间的距离变小
scale
// 手指捏合动作时的速率（加速度）
velocity
UIPinchGestureRecognizer *pinchGestureRecognizer = [[UIPinchGestureRecognizer alloc] init];
[pinchGestureRecognizer addTarget:self action:@selector(gestureRecognizerHandle:)];
[self.view addGestureRecognizer:pinchGestureRecognizer];
3.UIPanGestureRecognizer (摇动或者拖拽)
// 最少手指个数
minimumNumberOfTouches
// 最多手指个数
maximumNumberOfTouches
UIPanGestureRecognizer *panGestureRecognizer = [[UIPanGestureRecognizer alloc] init];
[panGestureRecognizer addTarget:self action:@selector(gestureRecognizerHandle:)];
[panGestureRecognizer setMinimumNumberOfTouches:1];
[panGestureRecognizer setMaximumNumberOfTouches:5];
[self.view addGestureRecognizer:panGestureRecognizer];
4.UISwipeGestureRecognizer (手指在屏幕上滑动操作手势)
// 滑动手指的个数
numberOfTouchesRequired
// 手指滑动的方向 （Up,Down,Left,Right）
direction
UISwipeGestureRecognizer *swipeGestureRecognizer = [[UISwipeGestureRecognizer alloc] init];
[swipeGestureRecognizer addTarget:self action:@selector(gestureRecognizerHandle:)];
[swipeGestureRecognizer setNumberOfTouchesRequired:2];
[swipeGestureRecognizer setDirection:UISwipeGestureRecognizerDirectionRight];
[self.view addGestureRecognizer:swipeGestureRecognizer];
5.UIRotationGestureRecognizer (手指在屏幕上旋转操作)
// 旋转方向，小于0为逆时针旋转手势，大于0为顺时针手势
rotation
// 旋转速率
velocity
UIRotationGestureRecognizer *rotationGestureRecognizer = [[UIRotationGestureRecognizer alloc] init];
[rotationGestureRecognizer addTarget:self action:@selector(gestureRecognizerHandle:)];
[self.view addGestureRecognizer:rotationGestureRecognizer];
6.UILongPressGestureRecognizer (长按手势)
numberOfTapsRequired
// 需要长按的手指的个数
numberOfTouchesRequired
// 需要长按的时间，最小为0.5s
minimumPressDuration
// 手指按住允许移动的距离
allowableMovement
UILongPressGestureRecognizer *longPressGestureRecognizer = [[UILongPressGestureRecognizer alloc] init];
[longPressGestureRecognizer addTarget:self action:@selector(gestureRecognizerHandle:)];
[longPressGestureRecognizer setMinimumPressDuration:1.0f];
[longPressGestureRecognizer setAllowableMovement:50.0];
[self.view addGestureRecognizer:longPressGestureRecognizer];
