iPhone - GestureRecognizer sometimes doesn't fire?

Question

I am trying to get a long key press on a button working in objective c for iPhone.

Here is the code I have put together for the GestureRecognizer:

    UILongPressGestureRecognizer *longPressGesture = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleLongPress:)];
    longPressGesture.minimumPressDuration = 1.0; //1 second
    longPressGesture.delegate = self;
    [deleteButton addGestureRecognizer:longPressGesture];
    [longPressGesture release];

And here is the function that I use in the selector to call when a long key press is detected.

-(void)handleLongPress:(UILongPressGestureRecognizer *) gestureRecognizer
{
    if (gestureRecognizer.state == UIGestureRecognizerStateBegan) {
        NSLog(@"Got handle long key press");
        NumLabel.text = @"";

    }

}

I have also added the following functions as part of my delegate class but they don't seem to have had any impact:

-(BOOL)gestureRecognizerShouldBegin:(UIGestureRecognizer *)gestureRecognizer{

    return YES;
}

-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldRecognizeSimultaneouslyWithGestureRecognizer:(UIGestureRecognizer *)otherGestureRecognizer{

    return NO;

}

-(BOOL)gestureRecognizer:(UIGestureRecognizer *)gestureRecognizer shouldReceiveTouch:(UITouch *)touch{

    return YES;

}

My issue is that this sometimes works but then again sometimes it doesn't, most of the time I get the call to handleLongPress and it works fine but every so often when the button is pressed and held down I get nothing until I lift my finger off the button at which stage my normal code for the button is run.

Have I missed something in the tutorials or can anyone spot why it would work sometimes but I get nothing on other occasions?

EDIT

I actually think the issue is with the way the button is pressed, if I press the button straight on and hold it then it works fine, however if my finger slips on the button even a little bit then the handleLongPress function isn't called.

I'm assuming this is because it recognizes it as a separate gesture? Is there a way to make sure that handleLongPress gets called as long as the button is held down even if the finger moves across the button at all?

Answer 1

Gesture recognizers are only for TOUCHES, not for button states. A Long press is really just pressing and releasing. When the touch moves, the gesture will be canceled!!
If you just want to know if your button is pressed more than a specific time, you can handle TouchDown/TouchCancel events of your button and add some timing.