触摸事件UITouch的应用

/*    定义属性 */@interface ViewController (){    CGPoint _startPoint; //开始点击的点    CGPoint _endPoint; //结束点击的点        UILabel *_label1; //显示当前触摸的状态的标签    UILabel *_label2;    UILabel *_label3;    UILabel *_label4;    UIImageView *_imageView; //笑脸图片}/*    触摸事件UITouch的系列方法如下所示 <一>到<四> */#PRagma mark <一> 当一个或多个手指触碰屏幕时，发送touchesBegan:withEvent:消息-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event{    _label1.text = @"触摸 开始 ";        //1. 首先获取触摸屏幕的手指    UITouch * touch = [touches anyObject];        //2. 点击的当前点的坐标    CGPoint point = [touch locationInView:self.view];    _label2.text = [NSString stringWithFormat:@"当前点得坐标:x=%.1f, y=%.1f",point.x,point.y];        //4. 获取触摸屏幕的次数    int tapCount = touch.tapCount;    //5. 获取触摸屏幕的手指根数    int fingerCount = touches.count;        _label3.text = [NSString stringWithFormat:@"触摸屏幕次数为%i, 触摸的手指数为%i",tapCount,fingerCount];        //6. 当前视图默认只支持单点触摸 如果想添加多点触摸 必须开启多点触摸模式    self.view.multipleTouchEnabled = YES;        //7.1. 得到开始点击的点,得到最后点击的点，计算一下，看看做了什么操作    _startPoint = [touch locationInView:self.view];    _label4.text = @"";}#pragma mark <二> 当一个或多个手指在屏幕上移动时，发送touchesMoved:withEvent:消息-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event{    _label1.text = @"触摸 move...";    CGPoint point = [[touches anyObject] locationInView:self.view];    _label2.text = [NSString stringWithFormat:@"当前点得坐标:x=%.1f, y=%.1f",point.x,point.y];}#pragma mark <三> 当一个或多个手指离开屏幕时，发送touchesEnded:withEvent:消息-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event{    _label1.text = @"触摸 结束";    CGPoint point = [[touches anyObject] locationInView:self.view];        //3. 判断是否进入了图片范围内    if (CGRectContainsPoint(_imageView.frame, point)) {        _label2.text = @"停留在笑脸图片范围内";    }    else    {        _label2.text = @"停留在笑脸图片外面";    }        //7.2 计算开始到结束偏移量    float distanceX = fabsf(point.x - _startPoint.x);    //获取手指纵向移动的偏移量    float distanceY = fabsf(point.y - _startPoint.y);        _label4.text = [NSString stringWithFormat:@"x偏移了%.1f，y方向偏移了%.1f",distanceX,distanceY];        _startPoint = CGPointZero;}#pragma mark <四> 当触摸序列被诸如电话呼入这样的系统事件打断所意外取消时，发送touchesCancelled:withEvent:消息-(void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event{    _label1.text = @"触摸 取消";}