//实例化长按手势监听
    UILongPressGestureRecognizer *longPress = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(btnLong:)];

    //代理
    longPress.delegate = self;
    longPress.minimumPressDuration = 0.5;

    [self.label_num addGestureRecognizer:longPress];