Multitouch basics (3 or more fingers)

I've noticed a lack of questions related to true multi-touch in iOS. I'm not talking about touch events for one finger, I'm talking about touch events for 3 or more fingers. Are there any sources or documentation articles about gesture handling for large amounts of touch input? And if not, are there any b开发者_JAVA技巧ase methods that any of you have used in the past that work?

(P.S. My ultimate goal is to NSLOG a 3 finger swipe down).

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Use gesture recognizers—they handle touch processing for you and most let you specify the minimum number of fingers for the gesture to be recognized. In your case, for example:

// -viewDidLoad
UISwipeGestureRecognizer *swipeRecognizer = [[UISwipeGestureRecognizer alloc] initWithTarget:self action:@selector(swiped:)];
swipeRecognizer.direction = UISwipeGestureRecognizerDirectionDown;
swipeRecognizer.numberOfTouchesRequired = 3;
[self.view addGestureRecognizer:swipeRecognizer];
[swipeRecognizer release];

…

- (void)swiped:(UISwipeGestureRecognizer *)recognizer
{
    if(recognizer.state == UIGestureRecognizerStateRecognized)
    {
        // got a three-finger swipe
    }
}