iOS开发笔记之多点触控（一）处理触摸的4个方法

多点触控乃苹果公司带给世界的创新之首，作为移动开发者，熟练掌握多点触控开发技能很有必要。

处理触摸的四个方法：

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event     //首次在屏幕上检测到触摸时调用
{
    NSLog(@"touchesBegan");
}

-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event     //如果触摸移动到了新的位置则会调用此方法
{
    NSLog(@"touchesMoved");
}

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event    //当触摸离开屏幕调用此方法
{
    NSLog(@"touchesEnded");
}

-(void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event    //如系统决定取消此次触摸，那可能就不调用touchesEnded方法了，在这种情况下会调用touchesCancelled方法
{
    NSLog(@"touchesCancelled");
}

快速点击屏幕，Debug窗口显示

 

2014-01-13 22:47:10.121 bbsTouch[593:70b] touchesBegan

2014-01-13 22:47:10.125 bbsTouch[593:70b] touchesEnded

2014-01-13 22:47:10.238 bbsTouch[593:70b] touchesBegan

2014-01-13 22:47:10.239 bbsTouch[593:70b] touchesEnded

2014-01-13 22:47:10.242 bbsTouch[593:70b] touchesBegan

2014-01-13 22:47:10.244 bbsTouch[593:70b] touchesEnded

 

点击并在屏幕上拖动，Debug窗口显示

 

2014-01-13 22:48:44.148 bbsTouch[593:70b] touchesBegan

2014-01-13 22:48:44.163 bbsTouch[593:70b] touchesMoved

2014-01-13 22:48:44.195 bbsTouch[593:70b] touchesMoved

2014-01-13 22:48:44.211 bbsTouch[593:70b] touchesMoved

2014-01-13 22:48:44.229 bbsTouch[593:70b] touchesMoved

2014-01-13 22:48:44.249 bbsTouch[593:70b] touchesMoved

2014-01-13 22:48:44.281 bbsTouch[593:70b] touchesMoved

2014-01-13 22:48:44.314 bbsTouch[593:70b] touchesMoved

2014-01-13 22:48:44.330 bbsTouch[593:70b] touchesMoved

2014-01-13 22:48:44.347 bbsTouch[593:70b] touchesMoved

2014-01-13 22:48:44.821 bbsTouch[593:70b] touchesEnded

 

touchesMoved可能不会在触摸队列中产生，然而，touchesBegan事件之后，总会产生touchesEnded或touchesCancelled事件。

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