Swift中实现点击、双击、捏、旋转、拖动、划动、长按手势的类和方法介绍

enum UIGestureRecognizerState : Int {

    case Possible // the recognizer has not yet recognized its gesture, but may be evaluating touch events. this is the default state

    case Began // the recognizer has received touches recognized as the gesture. the action method will be called at the next turn of the run loop     case Changed // the recognizer has received touches recognized as a change to the gesture. the action method will be called at the next turn of the run loop     case Ended // the recognizer has received touches recognized as the end of the gesture. the action method will be called at the next turn of the run loop and the recognizer will be reset to UIGestureRecognizerStatePossible     case Cancelled // the recognizer has received touches resulting in the cancellation of the gesture. the action method will be called at the next turn of the run loop. the recognizer will be reset to UIGestureRecognizerStatePossible

    case Failed // the recognizer has received a touch sequence that can not be recognized as the gesture. the action method will not be called and the recognizer will be reset to UIGestureRecognizerStatePossible }