Detecting the direction of PAN gesture in iOS

In the target selector of your gesture recognizer, use - (CGPoint)velocityInView:(UIView *)view;:

- (void)panRecognized:(UIPanGestureRecognizer *)rec
{
    CGPoint vel = [rec velocityInView:self.view];
    if (vel.x > 0)
    {
        // user dragged towards the right
        counter++;
    }
    else
    {
        // user dragged towards the left
        counter--;
    }
}

P.s.: I didn’t know about this method until approx. 3 minutes before. One of Google’s first hits was the official Apple documentation.