UIGestureRecognizer就是为了识别用户的手势，一共六个细分的手势，分别是：点击(tap)、长按(longPress)、滑动(swipe)、缩放(pinch)、旋转(rotation)、拖拽(pan)。

UIGestureRecognizer:

1.state

typedef NS_ENUM(NSInteger, UIGestureRecognizerState) {
    UIGestureRecognizerStatePossible,   
    UIGestureRecognizerStateBegan,      // 手势开始识别
    UIGestureRecognizerStateChanged,    // 手势改变（过程中）
    UIGestureRecognizerStateEnded,      // 手势结束
    UIGestureRecognizerStateCancelled,  // 手势取消
    UIGestureRecognizerStateFailed,     // 手势失败
    UIGestureRecognizerStateRecognized
};

2.locationInView

获取手势在视图中的位置

3.delegate

为了监听手势的各种行为

UITapGestureRecognizer(点击)

UITapGestureRecognizer *tapGesture = [[UITapGestureRecognizer alloc] initWithTarget:self  action:@selector(gesture:)];
tapGesture.numberOfTouchesRequired = 1;   //响应事件的手指数
tapGesture.numberOfTapsRequired = 1;     //响应事件的点击次数
[self.view addGestureRecognizer:tapGesture];

UILongPressGestureRecognizer(长按)

UILongPressGestureRecognizer *longGesture = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(gesture:)];
longGesture.minimumPressDuration = 1;    //响应事件的最小时间
longGesture.allowableMovement = 50;     //允许移动的距离范围
[self.view addGestureRecognizer:longGesture];

UISwipeGestureRecognizer(滑动)

UISwipeGestureRecognizer *swipeGesture = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(gesture:)];
swipeGesture.direction = UISwipeGestureRecognizerDirectionRight;    //滑动的方向
swipeGesture.numberOfTouchesRequired = 1;
[self.view addGestureRecognizer:swipeGesture];

UIPinchGestureRecognizer(缩放)

UIPinchGestureRecognizer *pinchGesture = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(gesture:)];
pinchGesture.scale = 2;    //缩放的比例
[self.view addGestureRecognizer:pinchGesture];

UIRotationGestureRecognizer(旋转)

UIRotationGestureRecognizer *rotationGesture = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotation:)];
rotationGesture.rotation = M_PI_2;
[self.view addGestureRecognizer:rotationGesture];

-(void)rotationGesture:(id)sender{
     UIRotateGestureRecognizer *gesture = sender;
     if (gesture.state==UIGestureRecognizerStateChanged) {
         _imageView.transform=CGAffineTransform=Rotation(_imageView.transform,gesture.rotation);
　  　}
　　  if (gesture.state==UIGestureRecognizerStateEnded) {
　　　　  [UIView animateWithDuration:1 animations:^{
　　　　  _imageView.transform=CGAffineTransformIdentity;    //取消形变
         }];
      }
 }

UIPanGestureRecognizer(拖拽)

UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(gesture:)];
panGesture.minimumNumberOfTouches = 1;
panGesture.maximumNumberOfTouches = 1;
[panGesture translationInView:self.view];
[_redView addGestureRecognizer:panGesture];