手势识别UIGestureRecognizer

同时识别多个手势，需要设置手势代理

1. <UIGestureRecognizerDelegate>

2.- (BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer {

    return YES;

}