UIView支持触摸事件 因为继承于UIResponder，而且支持多点触摸，使用时需要定义UIView子类，实现触摸相关的方法
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event；点击开始时执行此方法（多么见名知意）
- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event; 触摸结束时执行
- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event; 在屏幕上滑动时执行
- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event；当触摸序列被打断时（如电话）执行
例
// 点击视图改变颜色
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
// touches 是一个集合存储touche
// NSLog(@"%s %d", __func__, __LINE__);
// NSLog(@"%@ ----- %d", touches, [touches count]);
UITouch *touch = [touches anyObject];// 某一个手指
NSLog(@"%d", [touch tapCount]); // 点击次数
NSLog(@"%f", [touch timestamp]);
self.backgroundColor = [UIColorcolorWithRed:(arc4random() % 256)/255.0green:(arc4random() % 256)/255.0blue:(arc4random() % 256)/255.0alpha:1.0];
CGPoint location = [touch locationInView:self];
NSLog(@"%.1f %.1f", location.x, location.y);
NSLog(@"%@", touch.view); // 触摸所在的视图
NSLog(@"%@", touch.window); // 触摸事件所在的窗口
}