UISwipeGestureRecognizer Swipe length

Question

Any idea if there is a way to get the length of a swipe gesture or the touches so that i can calculate the distance?

Answer 1

I have an implementation similar to the answer in swift that discriminates between a drag and a swipe calculating the distance relative to the container and the speed of the swipe.

@objc private func handleSwipe(sender: UIPanGestureRecognizer) {
    if (sender.state == .began) {
        self.swipeStart.location = sender.location(in: self)
        self.swipeStart.time = Date()
    }
    else if (sender.state == .ended) {
        let swipeStopLocation : CGPoint = sender.location(in: self)
        let dx : CGFloat = swipeStopLocation.x - swipeStart.location.x
        let dy : CGFloat = swipeStopLocation.y - swipeStart.location.y
        let distance : CGFloat = sqrt(dx*dx + dy*dy );
        let speed : CGFloat = distance / CGFloat(Date().timeIntervalSince(self.swipeStart.time))
        let portraitWidth = min(self.frame.size.width, self.frame.size.height)
        print("Distance: \(distance), speed: \(speed), dy: \(dy), dx: \(dx), portraitWidth: \(portraitWidth), c1: \(distance >  portraitWidth * 0.4), c2: \(abs(dy) < abs(dx) * 0.25), c3: \(speed > portraitWidth * 3.0) ")
        if distance >  portraitWidth * 0.4 && abs(dy) < abs(dx) * 0.25 && speed > portraitWidth * 3.0 {
            if dx > 0 {
                delegate?.previousAssetPressed(self)
            }else{
                delegate?.nextAssetPressed(self)
            }
        }
    }
}