// 一个完整的触摸过程:touchesBegan -> touchesMoved -> touchesEnded
/*** 触摸开始(手指刚碰到view)
*/
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
/**
* 触摸ing(手指在view上面挪来挪去)
*/
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event
{
UITouch *touch = [touches anyObject];
// 当前触摸点
CGPoint current = [touch locationInView:self];
// 上一个触摸点
CGPoint previous = [touch previousLocationInView:self];
// 修改当前view的位置(中点)
CGPoint center = self.center;
center.x += current.x - previous.x;
center.y += current.y - previous.y;
self.center = center;
}
/**
* 触摸结束(手指离开view)
*/
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
/**
* 触摸手势取消(比如说来电时，手势也就中断了)
*/
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event