IOS开发—事件处理，触摸事件，UITouch，UIEvent，响应者链条，手势识别

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event

- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event

触摸产生时所处的窗口
@property(nonatomic,readonly,retain) UIWindow *window;

触摸产生时所处的视图
@property(nonatomic,readonly,retain) UIView *view;

短时间内点按屏幕的次数，可以根据tapCount判断单击、双击或更多的点击
@property(nonatomic,readonly) NSUInteger tapCount;

记录了触摸事件产生或变化时的时间，单位是秒
@property(nonatomic,readonly) NSTimeInterval timestamp;

当前触摸事件所处的状态
@property(nonatomic,readonly) UITouchPhase phase;

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

- (CGPoint)previousLocationInView:(UIView *)view;

@property(nonatomic,readonly) UIEventType type;
@property(nonatomic,readonly) UIEventSubtype subtype;

@property(nonatomic,readonly) NSTimeInterval timestamp;

触摸开始：- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
触摸移动：- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
触摸结束：- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
触摸取消（可能会经历）：- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event

// 什么时候调用:只要事件一传递给一个控件就会调用
// 作用:寻找最合适的view给你
// UIApplication -> [UIWindow hitTest:withEvent:]寻找最合适的view告诉系统
// point:当前手指触摸的点
// point:是方法调用者坐标系上的点
- (UIView *)hitTest:(CGPoint)point withEvent:(UIEvent *)event
{
//   UIView *fitView = [super hitTest:point withEvent:event];
    
    // 1.判断下窗口能否接收事件
    if (self.userInteractionEnabled == NO || self.hidden == YES || self.alpha <= 0.01) return nil;
    
    // 2.判断下点在不在窗口上
    // 不在窗口上
    if ([self pointInside:point withEvent:event] == NO) return nil;
    
    // 3.从后往前遍历子控件数组
    int count = (int)self.subviews.count;
    
    // 0 1
    for (int i = count - 1; i >= 0; i--) {
        // 获取子控件
        UIView *childView = self.subviews[i];
        
        // 坐标系的转换,把窗口上的点转换为子控件上的点
        // 把自己控件上的点转换成哪个控件上点
        CGPoint childP = [self convertPoint:point toView:childView];
        
         UIView *fitView = [childView hitTest:childP withEvent:event];
        
        if (fitView) {// 如果能找到最合适的view
            return fitView;
        }
    }
    // 4.没有比自己更合适的view
    return self;
}

// 作用:判断下传入过来的点在不在方法调用者的坐标系上
// point:是方法调用者坐标系上的点
- (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
{
    return NO;
}

UITapGestureRecognizer(敲击)
UIPinchGestureRecognizer(捏合，用于缩放)
UIPanGestureRecognizer(拖拽)
UISwipeGestureRecognizer(轻扫)
UIRotationGestureRecognizer(旋转)
UILongPressGestureRecognizer(长按)

创建手势识别器对象
UITapGestureRecognizer *tap = [[UITapGestureRecognizer alloc] init];

设置手势识别器对象的具体属性
// 连续敲击2次
tap.numberOfTapsRequired = 2;
// 需要2根手指一起敲击
tap.numberOfTouchesRequired = 2;

添加手势识别器到对应的view上
[self.iconView addGestureRecognizer:tap];

监听手势的触发
[tap addTarget:self action:@selector(tapIconView:)];

- (void)setUpLongPress
{
    // 长按手势
    UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(longPress:)];
    
    [_imageView addGestureRecognizer:longPress];

}

// 什么时候调用:长按的时候调用,而且只要手指不离开,拖动的时候会一直调用,手指抬起的时候也会调用
- (void)longPress:(UILongPressGestureRecognizer *)longPress
{
    // 注意：在以后开发中,长按手势一般需要做判断
    if (longPress.state == UIGestureRecognizerStateEnded) {
        
        NSLog(@"%s",__func__);
    }
}

- (void)setUpSwipe
{
    // 一个手势只能对应一个方向
    // 设置轻扫的方向往右（不设置的话默认为右）
    UISwipeGestureRecognizer *swipeR = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipe:)];
    
    // 设置轻扫的方向
    swipeR.direction = UISwipeGestureRecognizerDirectionRight;
    
    [_imageView addGestureRecognizer:swipeR];
    
    
    
    // 设置轻扫的方向往左
    UISwipeGestureRecognizer *swipe = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swipe:)];
    
    // 设置轻扫的方向
    swipe.direction = UISwipeGestureRecognizerDirectionLeft;
    
    [_imageView addGestureRecognizer:swipe];
}

- (void)swipe:(UISwipeGestureRecognizer *)swipe
{
    if (swipe.direction == UISwipeGestureRecognizerDirectionRight) {
        // 往右边轻扫 
    }else{
        // 往左边轻扫
        NSLog(@"%s左边",__func__);
    }
}

#pragma mark - 添加旋转手势
- (void)setUpRotation
{
    // 旋转
    UIRotationGestureRecognizer *rotation = [[UIRotationGestureRecognizer alloc] initWithTarget:self action:@selector(rotation:)];
    
    rotation.delegate = self;
    
    [_imageView addGestureRecognizer:rotation];
}
- (void)rotation:(UIRotationGestureRecognizer *)rotation
{
 
    // 获取的角度是相对于最原始的角度
    NSLog(@"%f",rotation.rotation);
    
    // 旋转图片
    _imageView.transform = CGAffineTransformRotate(_imageView.transform, rotation.rotation);
    
    // 复位,只要想相对于上一次旋转就复位
    rotation.rotation = 0;
    
}

#pragma mark - 添加捏合手势
- (void)setUpPinch
{
    // 捏合
    UIPinchGestureRecognizer *pinch = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(pinch:)];
    
    pinch.delegate = self;
    
    [_imageView addGestureRecognizer:pinch];
}

- (void)pinch:(UIPinchGestureRecognizer *)pinch
{
    
    _imageView.transform = CGAffineTransformScale(_imageView.transform, pinch.scale, pinch.scale);
    
    // 复位
    pinch.scale = 1;
}

- (void)viewDidLoad {
    [super viewDidLoad];

    // 拖拽手势
    UIPanGestureRecognizer *pan = [[UIPanGestureRecognizer alloc]
                                   initWithTarget:self action:@selector(pan:)];
    
    [_imageView addGestureRecognizer:pan];
}

- (void)pan:(UIPanGestureRecognizer *)pan
{
    
    // 获取手指平移的偏移量
    CGPoint transP = [pan translationInView:_imageView];
    
    _imageView.transform = CGAffineTransformTranslate(_imageView.transform, transP.x, transP.y);

    // 复位
    [pan setTranslation:CGPointZero inView:_imageView];
}

// Simultaneously:同时
// 是否同时支持多个手势
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer
{
    return YES;
}

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
};