prevent touchdown IBAction event from firing when UITapGestureRecognizer fires on double tap - iphone

Question

I have two IBActions applied to a button one of which fires on touchdown and down and the other on touch up, however I also have a tap gesture applied to the button that fires on a double tap.
I've applied NSLog to see whats happening and the result is that both the touchdown and double tap fire when I double tap (fortunately the touch up doesn't fire) which makes sense - but how do i prevent the touch down firing when I double tap?
Code example
//fired on touch down
-(IBAction)touchdown:(id)sender
{
NSLog(#"touching down.");
}
//fired on touch up
-(IBAction)touchup:(id)sender
{
NSLog(#"taking off.");
}
//fired on double click
-(IBAction)boost:(UITapGestureRecognizer *)sender
{
NSLog(#"goodbye.");
}

Answer 1

Import the delegate, <UIGestureRecognizerDelegate>
I think you done this in viewDidLoad Method,
UITapGestureRecognizer *tapGestureRecognizer = [[UITapGestureRecognizer alloc] initWithTarget:self action:#selector(boost:)];
tapGestureRecognizer.delegate = self;
tapGestureRecognizer.numberOfTapsRequired = 2;
[self.button addGestureRecognizer:tapGestureRecognizer];
You need to implement this delegate method, based on your touch down coordinates,
-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch
{
CGPoint coords = [touch locationInView:self.button];
NSLog(#"Coords: %g, %g", coords.x, coords.y);
if (coords.y < 21 && coords.y > 25)
return NO;
else
return YES;
}