iOS手势-UIGestureRecognizer

1. UIGestureRecognizer

父类是NSObject

利用手势识别器---UIGestureRecognizer，能轻松识别用户在某个view上面做的一些常见手势
UIGestureRecognizer是一个抽象类，定义了所有手势的基本行为，使用它的子类才能处理具体的手势，详见其子类介绍
一个手势只能支持一个方向
默认只支持一个手势，若要实现多个手势，需要设置手势代理，遵守<UIGestureRecognizerDelegate>，并实现shouldRecognizeSimultaneouslyWithGestureRecognizer，返回YES。

2. 手势识别的状态

手势状态	含义
UIGestureRecognizerStatePossible	没有触摸事件发生，所有手势识别的默认状态
UIGestureRecognizerStateBegan	一个手势已经开始但尚未改变或者完成时
UIGestureRecognizerStateChanged	手势状态改变
UIGestureRecognizerStateEnded	手势完成
UIGestureRecognizerStateCancelled	手势取消，恢复至Possible状态
UIGestureRecognizerStateFailed	手势失败，恢复至Possible状态
UIGestureRecognizerStateRecognized = UIGestureRecognizerStateEnded	识别到手势识别

3. UIGestureRecognizer属性

// 手势状态
@property(nonatomic,readonly) UIGestureRecognizerState state;

//手势代理
@property(nullable,nonatomic,weak) id <UIGestureRecognizerDelegate> delegate;

// 手势是否可用（默认可用）
// 当前在识别手势时不能修改手势是否可用
@property(nonatomic, getter=isEnabled) BOOL enabled;

// 手势的视图
@property(nullable, nonatomic,readonly) UIView *view;

@property(nonatomic) BOOL cancelsTouchesInView;
@property(nonatomic) BOOL delaysTouchesBegan;
@property(nonatomic) BOOL delaysTouchesEnded;

@property(nonatomic, copy) NSArray<NSNumber *> *allowedTouchTypes
@property(nonatomic, copy) NSArray<NSNumber *> *allowedPressTypes

4. UIGestureRecognizer方法


// 初始化手势，直接用initWithTarget就好，另外两个忽略
//     -(void)handleGesture;
//     -(void)handleGesture:(UIGestureRecognizer*)gestureRecognizer;
- (instancetype)initWithTarget:(nullable id)target action:(nullable SEL)action

// 增加监听和移除监听

(void)addTarget:(id)target action:(SEL)action;
(void)removeTarget:(nullable id)target action:(nullable SEL)action; //target为nil，则移除所有相同方法名的方法

// 获取touch的位置

(CGPoint)locationInView:(nullable UIView*)view;

// 获取locations中的touches的数量

(NSUInteger)numberOfTouches;

// 获取特定角标的touch的位置

(CGPoint)locationOfTouch:(NSUInteger)touchIndex inView:(nullable UIView*)view;
(void)requireGestureRecognizerToFail:(UIGestureRecognizer *)otherGestureRecognizer;
@end

5. UIGestureRecognizer的代理--UIGestureRecognizerDelegate


// 是否允许触发当前手势
- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer;

// Simultaneously:同时 sɪml’teɪnɪəslɪ
// 是否允许同时支持多个手势

(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer;

// 是否接收触摸手势

(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch;

// 是否接收按压手势

(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceivePress:(UIPress *)press;
(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRequireFailureOfGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer NS_AVAILABLE_IOS(7_0);
(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldBeRequiredToFailByGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer NS_AVAILABLE_IOS(7_0);