你真的了解UIGestureRecognizer吗？

一：首先查看一下关于UIGestureRecognizer的定义

//当前手势状态

typedef NS_ENUM(NSInteger, UIGestureRecognizerState) {

    //尚未识别是何种手势操作（但可能已经触发了触摸事件），默认状态

    UIGestureRecognizerStatePossible,

    //手势已经开始，此时已经被识别，但是这个过程中可能发生变化，手势操作尚未完成

    UIGestureRecognizerStateBegan,

    //手势状态发生改变

    UIGestureRecognizerStateChanged,

    // 手势识别操作完成（此时已经松开手指）

    UIGestureRecognizerStateEnded,

    //手势被取消，恢复到默认状态

    UIGestureRecognizerStateCancelled,

    //手势识别失败，恢复到默认状态

    UIGestureRecognizerStateFailed,

    //手势识别完成，同end

    UIGestureRecognizerStateRecognized = UIGestureRecognizerStateEnded

};

NS_CLASS_AVAILABLE_IOS(3_2) @interface UIGestureRecognizer : NSObject

//创建一个手势对象并添加触发事件

- (instancetype)initWithTarget:(nullable id)target action:(nullable SEL)action NS_DESIGNATED_INITIALIZER;

//给一个手势对象添加监听事件

- (void)addTarget:(id)target action:(SEL)action;

//移除一个手势的监听事件

- (void)removeTarget:(nullable id)target action:(nullable SEL)action;

//获取当前手势状态

@property(nonatomic,readonly) UIGestureRecognizerState state;

//委托

@property(nullable,nonatomic,weak) id <UIGestureRecognizerDelegate> delegate;

//手势识别是否可用

@property(nonatomic, getter=isEnabled) BOOL enabled;

//获取手势触摸的View视图 只读

@property(nullable, nonatomic,readonly) UIView *view;

//是否取消触摸控件的响应

默认为YES，这种情况下当手势识别器识别到触摸之后，会发送touchesCancelled给触摸到的控件以取消控件view对touch的响应，这个时候只有手势识别器响应touch，当设置成NO时，手势识别器识别到触摸之后不会发送touchesCancelled给控件，这个时候手势识别器和控件view均响应touch。

注意：手势识别和触摸事件是同时存在的，只是因为touchesCancelled导致触摸事件失效、

@property(nonatomic) BOOL cancelsTouchesInView;

//是否延迟发送触摸事件给触摸到的控件

默认是NO，这种情况下当发生一个触摸时，手势识别器先捕捉到到触摸，然后发给触摸到的控件，两者各自做出响应。如果设置为YES，手势识别器在识别的过程中（注意是识别过程），不会将触摸发给触摸到的控件，即控件不会有任何触摸事件。只有在识别失败之后才会将触摸事件发给触摸到的控件，这种情况下控件view的响应会延迟约0.15ms。

@property(nonatomic) BOOL delaysTouchesBegan;

//如果触摸识别失败是否立即结束本次手势识别的触摸事件

@property(nonatomic) BOOL delaysTouchesEnded;

//指定一个手势需要另一个手势执行失败才会执行，同时触发多个手势使用其中一个手势的解决办法

有时手势是相关联的，如单机和双击，点击和长按，点下去瞬间可能只会识别到单击无法识别其他，该方法可以指定某一个 手势，即便自己已经满足条件了，也不会立刻触发，会等到该指定的手势确定失败之后才触发

- (void)requireGestureRecognizerToFail:(UIGestureRecognizer *)otherGestureRecognizer;

//获取当前触摸在指定视图上的点

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

//获取触摸手指数

- (NSUInteger)numberOfTouches;

//多指触摸的触摸点相对于指定视图的位置

- (CGPoint)locationOfTouch:(NSUInteger)touchIndex inView:(nullable UIView*)view;

@end

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

知识点1：关于UIGestureRecognizer的子类如下（下面这些才是我们平常会直接运用到的类）：

UITapGestureRecognizer（轻触，点按）

UILongPressGestureRecognizer（长按）

UISwipeGestureRecognizer（轻扫手势）

UIRotationGestureRecognizer（旋转手势）

UIPanGestureRecognizer（拖拽手势）

UIPinchGestureRecognizer（捏合手势，缩放用）

实例如下：

//拖拽手势

UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(pan:)];

[tagButton addGestureRecognizer:pan];

- (void)pan:(UIPanGestureRecognizer *)pan

{

｝

//给视图增加点击动作

UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc]initWithTarget:self action:@selector(tapHandle:)];

[self.view addGestureRecognizer:tap];

-(void)tapHandle:(UITapGestureRecognizer*)tap

{

}

二：关于UIGestureRecognizerDelegate代理的内容

@protocol UIGestureRecognizerDelegate <NSObject>

@optional

//开始进行手势识别时调用的方法，返回NO则结束识别，不再触发手势，用处：可以在控件指定的位置使用手势识别

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer;

//是否支持多手势触发，返回YES，则可以多个手势一起触发方法，返回NO则为互斥

是否允许多个手势识别器共同识别，一个控件的手势识别后是否阻断手势识别继续向下传播，默认返回NO；如果为YES，响应者链上层对象触发手势识别后，如果下层对象也添加了手势并成功识别也会继续执行，否则上层对象识别后则不再继续传播

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

// 这个方法返回YES，第一个手势和第二个互斥时，第一个会失效

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRequireFailureOfGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer NS_AVAILABLE_IOS(7_0);

//这个方法返回YES，第一个和第二个互斥时，第二个会失效

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldBeRequiredToFailByGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer NS_AVAILABLE_IOS(7_0);

//手指触摸屏幕后回调的方法，返回NO则不再进行手势识别，方法触发等

此方法在window对象在有触摸事件发生时，调用gesture recognizer的touchesBegan:withEvent:方法之前调用，如果返回NO,则gesture recognizer不会看到此触摸事件。(默认情况下为YES)

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

@end

知识点1：

//是否同时支持多种手势

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer{

  return YES;

}

//是否允许开始点击

- (BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer{

return YES;

}

//设置点击的范围

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch{

//获取当前的触摸点

  CGPoint curp = [touch locationInView:self.imageView];

  if (curp.x <= self.imageView.bounds.size.width*0.5) {

      return NO;

  }else{

      return YES;

  }

}

知识点2：UITapGestureRecognizer和UIButton的点击事件冲突的解决办法

- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch{

if ([touch.view isKindOfClass:[UIButton class]])    {

       return NO;    }

       return YES;

}

三：关于UIGestureRecognizer的子类知识

1:UITapGestureRecognizer（轻触，点按）

NS_CLASS_AVAILABLE_IOS(3_2) @interface UITapGestureRecognizer : UIGestureRecognizer

//设置能识别到手势的最少的轻触次数（默认为1）

@property (nonatomic) NSUInteger  numberOfTapsRequired;

//设置能识别到手势的最少的手指的个数（默认为1）

@property (nonatomic) NSUInteger  numberOfTouchesRequired;

@end

知识点1：实例代码如下

// 创建一个手势对象

UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] initWithTarget:self action:@selector(tapAction:)];

// 设置能识别到手势的最少的轻触次数

tap.numberOfTapsRequired = ;

// 设置能识别到手势的最少的手指的个数

tap.numberOfTouchesRequired = ;

//把手势对象添加到对应的控件中

[self.imgView addGestureRecognizer:tap];

2：UILongPressGestureRecognizer（长按手势）

NS_CLASS_AVAILABLE_IOS(3_2) @interface UILongPressGestureRecognizer : UIGestureRecognizer

//设置能识别到手势的最少的轻触次数（默认为1）

@property (nonatomic) NSUInteger numberOfTapsRequired;

//设置能识别到手势的最少的手指的个数（默认为1）

@property (nonatomic) NSUInteger numberOfTouchesRequired;

//设置能识别到长按手势的最短的长按时间，单位：秒，默认为0.5

@property (nonatomic) CFTimeInterval minimumPressDuration;

//设置长按时允许移动的最大距离，单位：像素，默认为10像素

@property (nonatomic) CGFloat allowableMovement;

@end

知识点1：实例代码如下

UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPressAction:)];

// 设置能识别到长按手势的最小的长按时间

longPress.minimumPressDuration = 0.5;

// "容错的范围"

longPress.allowableMovement  = ;

// 把长按手势添加到对应的控件中

[self.imgView addGestureRecognizer:longPress];

3：UISwipeGestureRecognizer（轻扫手势）

typedef NS_OPTIONS(NSUInteger, UISwipeGestureRecognizerDirection) {

    UISwipeGestureRecognizerDirectionRight =  << ,  //向右滑

    UISwipeGestureRecognizerDirectionLeft  =  << ,  //向左滑

    UISwipeGestureRecognizerDirectionUp    =  << ,  //向上滑

    UISwipeGestureRecognizerDirectionDown  =  <<   //向下滑

};

NS_CLASS_AVAILABLE_IOS(3_2) @interface UISwipeGestureRecognizer : UIGestureRecognizer

//最少触摸手指个数，默认为1

@property(nonatomic) NSUInteger                        numberOfTouchesRequired;

//设置轻扫手势支持的方向，默认为向右滑

@property(nonatomic) UISwipeGestureRecognizerDirection direction;

@end

知识点1：实例代码如下

UISwipeGestureRecognizer *swipeLeft = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipeAction:)];

swipeLeft.direction = UISwipeGestureRecognizerDirectionLeft;

[self.imgView addGestureRecognizer:swipeLeft];

4：UIRotationGestureRecognizer（旋转手势）

NS_CLASS_AVAILABLE_IOS(3_2) @interface UIRotationGestureRecognizer : UIGestureRecognizer

//旋转的角度

@property (nonatomic)          CGFloat rotation;

//旋转速度，单位：度/秒、

@property (nonatomic,readonly) CGFloat velocity;

@end

知识点1：实例代码如下

//为图片框添加一个旋转手势

UIRotationGestureRecognizer *rotation = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotateAction:)];rotation.delegate = self;

[self.imgView addGestureRecognizer:rotation];

// 旋转手势的监听方法

- (void)rotateAction:(UIRotationGestureRecognizer *)recognizer {

// 在原来的基础上, 累加多少度

recognizer.view.transform = CGAffineTransformRotate(recognizer.view.transform, recognizer.rotation);

// 每次旋转完毕后将rotation的值, 恢复到0的位置.recognizer.rotation = 0;

}

5：UIPanGestureRecognizer（拖拽手势）

NS_CLASS_AVAILABLE_IOS(3_2) @interface UIPanGestureRecognizer : UIGestureRecognizer

//设置触发拖拽最少手指数，默认为1

@property (nonatomic)          NSUInteger minimumNumberOfTouches;

//设置触发拖拽最多手指数，默认为 UINT_MAX 无限大

@property (nonatomic)          NSUInteger maximumNumberOfTouches;

//获取当前拖拽位置

- (CGPoint)translationInView:(nullable UIView *)view;

//设置当前拖拽位置

- (void)setTranslation:(CGPoint)translation inView:(nullable UIView *)view;

//设置拖拽速度，单位：像素/秒

- (CGPoint)velocityInView:(nullable UIView *)view;

@end

知识点1：实例代码

UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panAction:)];

[self.imgView addGestureRecognizer:pan];

// 拖拽手势的监听方法

- (void)panAction:(UIPanGestureRecognizer *)recognizer {

// 1. 获取手指拖拽的时候, 平移的值

CGPoint translation = [recognizer translationInView:recognizer.view];

// 2. 让当前控件做响应的平移

recognizer.view.transform = CGAffineTransformTranslate(recognizer.view.transform, translation.x, translation.y);

// 3. 每次平移手势识别完毕后, 让平移的值不要累加

[recognizer setTranslation:CGPointZero inView:recognizer.view];

}

6：UIPinchGestureRecognizer（捏合手势，缩放用）

NS_CLASS_AVAILABLE_IOS(3_2) @interface UIPinchGestureRecognizer : UIGestureRecognizer

//设置缩放比例

@property (nonatomic)          CGFloat scale;

//获取捏合速度，单位：缩放比/秒

@property (nonatomic,readonly) CGFloat velocity;

@end

知识点1：实例代码

UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinchAction:)];

pinch.delegate = self;

[self.imgView addGestureRecognizer:pinch];

// 捏合手势监听方法

- (void)pinchAction:(UIPinchGestureRecognizer *)recognizer {

recognizer.view.transform = CGAffineTransformScale(recognizer.view.transform, recognizer.scale, recognizer.scale);

recognizer.scale = 1.0;

}