//去寻找最适合的View，返回第一响应者，即触碰点的视图
    -(UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
    // 用来判断某一个点击的位置是否在视图范围内，如果在就返回YES,继续遍历该视图的子视图；  
    如果返回NO，则不再遍历它的子视图；
    - (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event

    //hitTest:withEvent:底层实现
    - (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event {
        // 1.判断自己能否接收触摸事件
        if (self.userInteractionEnabled == NO || self.hidden == YES || self.alpha <= 0.01) return nil;
        // 2.判断触摸点在不在自己范围内
        if (![self pointInside:point withEvent:event]) return nil;
        // 3.从后往前遍历自己的子控件，看是否有子控件更适合响应此事件
        int count = self.subviews.count;
        for (int i = count - 1; i >= 0; i--) {
            UIView *childView = self.subviews[i];
            CGPoint childPoint = [self convertPoint:point toView:childView];
            UIView *fitView = [childView hitTest:childPoint withEvent:event];
            if (fitView) {
                return fitView;
            }
        }
        // 没有找到比自己更合适的view
        return self;
    }

                 UIWindow
        A1          A2        A3
      C1  c2     B1 B2 B3     D1

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
-(void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
-(void)touchesMoved:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event
-(void)touchesCancelled:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event

@implementation WGView
-(instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        self.backgroundColor = [UIColor redColor];
    }
    return self;
}
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    NSLog(@"WGView点击了");
}
@end

@implementation WGView1
-(instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        self.backgroundColor = [UIColor yellowColor];
    }
    return self;
}
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    NSLog(@"WGView1点击了");
}
@end

@implementation WGMainObjcVC
- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    WGView *view = [[WGView alloc]initWithFrame:CGRectMake(0, 100, 300, 200)];
    [self.view addSubview:view];
    
    WGView1 *view1 = [[WGView1 alloc]initWithFrame:CGRectMake(50, 150, 150, 80)];
    [view addSubview:view1];
}

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    NSLog(@"WGMainObjcVC.view触摸事件响应了");
}
@end

打印结果:  WGView1点击了   (点击WGView1的区域)

@implementation WGView1
-(instancetype)initWithFrame:(CGRect)frame {
    if (self = [super initWithFrame:frame]) {
        self.backgroundColor = [UIColor yellowColor];
    }
    return self;
}
- (void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    [super touchesBegan:touches withEvent:event];
    NSLog(@"WGView1点击了");
}
@end

打印结果: WGView点击了    (点击WGView1的区域)
        WGView1点击了 

初试化一个手势对象，并且设置响应对象和响应事件
- (instancetype)initWithTarget:(nullable id)target action:(nullable SEL)action;
没有绑定事件的初始化方法
- (instancetype)init;
- (nullable instancetype)initWithCoder:(NSCoder *)coder;

为手势添加响应者和响应事件
- (void)addTarget:(id)target action:(SEL)action;
 
移除指定响应者的响应事件
- (void)removeTarget:(nullable id)target action:(nullable SEL)action;
 
当前手势的状态
@property(nonatomic,readonly) UIGestureRecognizerState state;
 
手势的代理
@property(nullable,nonatomic,weak) id <UIGestureRecognizerDelegate> delegate;
 
是否启用手势识别，默认是YES，如果设置为NO，则表示不能识别手势，如果有正在识别的手势，则也会被取消
@property(nonatomic, getter=isEnabled) BOOL enabled;
     
点击屏幕次数 只读
@property(nonatomic, readonly) NSUInteger numberOfTouches;

ios(11.0)手势名称，主要用来调试
@property (nullable, nonatomic, copy) NSString *name;

手势添加到的视图，一般通过addGestureRecognizer:方法来设置
@property(nullable, nonatomic,readonly) UIView *view;
 
默认是YES，设置为YES时，当手势识别器识别到touch后，会发送touchesCancelled:或pressesCancelled:方法
给hit-testView来取消hit-testView对touch的响应，这个时候只有手势识别器可以响应touch，即触摸事件不会被触发
当设置为NO时，当手势识别器识别到touch后，不会再发送touchesCancelled:和pressesCancelled:方法给hit-testView，
即手势识别器和hit-testView都会响应touch
@property(nonatomic) BOOL cancelsTouchesInView;
 
默认是NO，设置为NO时，当发生一个touch时，手势识别器先捕获到touch,然后再发送给hit-testview，两者各自作出响应
设置为YES时，手势识别器在识别touch的过程中，不会再发送touch给hit-testview，即hit-testview不会有任何触摸事件；
只有在识别失败之后才会将touch发给hit-testview，这种情况下hit-testview的响应会延迟约0.15ms。
@property(nonatomic) BOOL delaysTouchesBegan;

默认是YES，设置为YES时，当发生一个touch时，在手势识别成功后，给hit-testview发送touchesEnded:或pressesEnded:消息；如果手势
识别失败，会延迟大概0.15ms,期间没有接收到别的touch时才会发送touchesEnded:或pressesEnded:
设置为NO时，则不会延迟，即会立即发送touchesEnded:或pressesEnded:以结束当前触摸。
@property(nonatomic) BOOL delaysTouchesEnded;

支持的TouchTypes.
@property(nonatomic, copy) NSArray<NSNumber *> *allowedTouchTypes;
 
支持的UIPress属性
@property(nonatomic, copy) NSArray<NSNumber *> *allowedPressTypes;

默认是YES，当设置为YES时,如果新的手势和旧的类型不匹配,新手势将会被手势识别器自动忽略.
当设置为NO时,手势识别器会识别allowedTouchTypes里面支持类型的手势
@property (nonatomic) BOOL requiresExclusiveTouchType;

例子 [A requireGestureRecognizerToFail: B] 手势A进行识别和执行的前提是 手势B失败了
- (void)requireGestureRecognizerToFail:(UIGestureRecognizer *)otherGestureRecognizer;

 获取手指点击屏幕实时的坐标点
- (CGPoint)locationInView:(nullable UIView*)view;

返回指定视图中第几个触摸点的坐标系
- (CGPoint)locationOfTouch:(NSUInteger)touchIndex inView:(nullable UIView*)view;

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

默认是NO，是否允许两个手势同时识别； 设置YES:可以保证同时识别   
设置NO：不能保证不同时识别，因为其他手势代理可能设置为YES
- (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;

//下面两个方法用来控制手势的互斥执行的
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;
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;

typedef NS_ENUM(NSInteger, UIGestureRecognizerState) {
    UIGestureRecognizerStatePossible, 默认的状态，这个时候的手势并没有具体的情形状态
    UIGestureRecognizerStateBegan,   手势开始被识别的状态，但尚未改变或者完成时
    UIGestureRecognizerStateChanged,    手势识别发生改变的状态
    UIGestureRecognizerStateEnded,      手势识别完成，将会执行触发的方法
    UIGestureRecognizerStateCancelled,  手势识别取消，恢复到默认状态
    UIGestureRecognizerStateFailed,     识别失败，方法将不会被调用，恢复到默认状态
    UIGestureRecognizerStateRecognized = UIGestureRecognizerStateEnded
};

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc]  
    initWithTarget:self action:@selector(clickTap)];
    [self.view addGestureRecognizer:tap];
}

-(void)clickTap {
    for (int i = 0; i < 10; i++) {
        NSLog(@"点击可tap");
    }
}

-(void)touchesBegan:(NSSet<UITouch *> *)touches withEvent:(UIEvent *)event {
    for (int i = 0; i < 10; i++) {
        NSLog(@"点击了屏幕");
    }
}

- (void)viewDidLoad {
    [super viewDidLoad];
    self.view.backgroundColor = [UIColor whiteColor];
    UIButton *btn = [[UIButton alloc]initWithFrame:CGRectMake(100, 100, 100, 30)];
    btn.backgroundColor = [UIColor redColor];
    [btn addTarget:self action:@selector(clickBtn) forControlEvents:UIControlEventTouchUpInside];
    [self.view addSubview:btn];
    
    UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc]initWithTarget:self   
    action:@selector(clickTap)];
    [btn addGestureRecognizer:tap];
}

-(void)clickBtn {
    NSLog(@"点击按钮---addTarget");
}

-(void)clickTap {
    NSLog(@"点击按钮---UITapGestureRecognizer");
}

打印结果: 点击按钮---UITapGestureRecognizer