gestureRecognizer

1. singletap.delegate = self;
 singletap = [[UITapGestureRecognizeralloc] initWithTarget:selfaction:@selector(handleSingleTap:)];

 2. 下面的函数是委托，查看头文件说明（// called before touchesBegan:withEvent: is called on the gesture recognizer for a new touch. return NO to prevent the gesture recognizer from seeing this touch） 意思是，当委托返回NO，将会阻止点击的事件,即不掉用3中的方法
- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch;

 3.(void) handleSingleTap:(UITapGestureRecognizer *) gestureRecognizer｛｝