- (IBAction)panToControlNum:(UIPanGestureRecognizer *)sender
{
    CGPoint vel = [sender velocityInView:self.view];
    switch (sender.state)
    {
	case UIGestureRecognizerStateChanged:

        if (vel.y < 0)
        {   // user dragged towards the up
           vel.y = 0;
           num++;
        }
        else if(vel.y > 0)
       {   // user dragged towards the down
           vel.y = 0;
           num--;
       }
        case UIGestureRecognizerStateEnded:
            NSLog(@"pan gesture start ened , do nothing");
            break;

        default:
            break;
    }
}
@end