use implement and use a gesture

Gesture.m

- (void)setPannableView:(UIView *)pannableView // maybe this is a setter in a Controller
    {
        _pannableView = pannableView;
        UIPanGestureRecognizer *pangr =
            [[UIPanGestureRecognizer alloc] initWithTarget:pannableView action:@selector(pan:)];
        [pannableView addGestureRecognizer:pangr];
}


//implement a gesture
- (void)pan:(UIPanGestureRecognizer *)recognizer
{
    if ((recognizer.state == UIGestureRecognizerStateChanged) ||
    (recognizer.state == UIGestureRecognizerStateEnded)) {
        CGPoint translation = [recognizer translationInView:self];
        // move something in myself (I’m a UIView) by translation.x and translation.y
        // for example, if I were a graph and my origin was set by an @property called origin 
        self.origin = CGPointMake(self.origin.x+translation.x, self.origin.y+translation.y); 
        [recognizer setTranslation:CGPointZero inView:self];
    } 
}

/******Gesture method******/
//how far the gesture move
- (CGPoint)translationInView:(UIView *)aView;
//how fast the gesture move
- (CGPoint)velocityInView:(UIView *)aView;
//reset the translation
- (void)setTranslation:(CGPoint)translation inView:(UIView *)aView;