iOS触摸事件学习

部分内容摘自：http://www.cnblogs.com/kenshincui/p/3950646.html

触摸事件
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event;	一根或多根手指开始触摸屏幕时执行；
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event;	一根或多根手指在屏幕上移动时执行，注意此方法在移动过程中会重复调用；
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event;	一根或多根手指触摸结束离开屏幕时执行；
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event;	触摸意外取消时执行（例如正在触摸时打入电话）；

在事件处理函数中从touches（NSSet*）中获得UITouch对象，通过该对象来获得触摸时相应的状态参数等，常用的方法及属性有：

1. - (CGPoint)locationInView:(UIView *)view

Returns the current location of the receiver in the coordinate system of the given view.

返回“当前触点”在给定视图中的坐标

2. - (CGPoint)previousLocationInView:(UIView *)view

Returns the previous location of the receiver in the coordinate system of the given view.

返回“上一个触点”在给定视图中的坐标

3.@property(nonatomic, readonly, retain) UIView *view

The view in which the touch initially occurred. (read-only)

发生触发的视图（只读）

4.@property(nonatomic, readonly, retain) UIWindow *window

The window in which the touch initially occurred. (read-only)

发生触发的窗口（只读）

5.@property(nonatomic, readonly) NSUInteger tapCount

The number of times the finger was tapped for this given touch. (read-only)

点击次数（只读）短期内

6.@property(nonatomic, readonly) NSTimeInterval timestamp

The time when the touch occurred or when it was last mutated. (read-only)

触摸产生或变化的时间戳（只读）

7.对UIEvent对象：

- (NSSet *)touchesForView:(UIView *)view

Returns the touch objects that belong to a given view for the event represented by the receiver.

返回位于给定的视图的触摸集合。