"Make a Custom UIGestureRecognizer in Objective-C" Touches Ended & Cancelled Methods.

ZLetterGestureRecognizer.m

-(void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
   [super touchesEnded:touches withEvent:event]; 
   [self reset];
}
-(void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
   self.state = UIGestureRecognizerStateCancelled;
   [self reset];
}