iOS目前支持的手势识别
UITapGestureRecognizer(点按)
UipinchGestureRecognizer(捏合)
UIPanGestureRecognizer(拖动)
UISwipeGestureRecognizer(轻扫)
UIRotationGestureRecognizer(旋转)
UILongPRessGestureRecognizer(长按)
手势识别的状态
typedef NS_ENUM(NSInteger, UIGestureRecognizerState) {//没有触摸事件发生，所有手势识别的默认状态UIGestureRecognizerStatePossible,//一个手势已经开始但尚未改变或者完成时UIGestureRecognizerStateBegan,//手势状态改变UIGestureRecognizerStateChanged,//手势完成UIGestureRecognizerStateEnded,//手势取消，恢复至Possible状态UIGestureRecognizerStateCancelled,//手势失败，恢复至Possible状态UIGestureRecognizerStateFailed,//识别到手势识别UIGestureRecognizerStateRecognized =UIGestureRecognizerStateEnded
};
提示：UITapGestureRecognizer也被称为离散手势，该手势识别不会被取消，只是调用一次selector任务
手势识别的使用方法
1. 创建手势识别实例
2. 设置手势识别属性，例如手指数量，方向等
3. 将手势识别附加到指定的视图之上
4. 编写手势触发监听方法