Call function when SwipeGestureRecognizer swipe speed passes threshold

Question

I'm currently programming an app, which contains a UIView with a UISwipeGestureRecognizer

I want the recognizer to recognize how fast the user is dragging in the recognizer's direction. When the speed is high enough (past a specific threshold) a custom action should occur. It's basically the same as in this post, but I need it written in Swift.

How do I translate that to Swift or is there a better way to do it?

Current Code, Xcode Errors marked as comments.

Touches began:

override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {


        //avoid multi-touch gesture
        if(touches.count > 1){
            return;
        }

        if let touch:UITouch = touches.first as? UITouch{
            let locator:CGPoint = touch.locationInView(self.view!)
            start = locator
            startTime = touch.timestamp
        }

Touches ended:

    override func touchesEnded(touches: Set<NSObject>, withEvent event: UIEvent) {

    if let touch:UITouch = touches.first as? UITouch{
        let locator:CGPoint = touch.locationInView(self.view!)

        var dx:CGFloat = (locator.x - start!.x);
        var dy:CGFloat = (locator.y - start!.y);
        var magnitude:CGFloat = sqrt(dx*dx+dy*dy)

        if (magnitude >= kMinDistance) {
            // Determine time difference from start of the gesture
            var dt:CGFloat = CGFloat(touch.timestamp - startTime!)
            if (dt > kMinDuration) {
                // Determine gesture speed in points/sec
                var speed:CGFloat = magnitude / dt;
                 if (speed >= kMinSpeed && speed <= kMaxSpeed) {
                    // Swipe detected
                    swipedView()
    }}}}}

Answer 1

var start:CGPoint?
var startTime:NSTimeInterval?

var kMinDistance:CGFloat   = 25.0
var kMinDuration:CGFloat   = 0.1
var kMinSpeed:CGFloat      = 100.0
var kMaxSpeed:CGFloat      = 500.0

override func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {
    //avoid multi-touch gesture
    if(touches.count > 1){
        return;
    }

    if let touch:UITouch = touches.first as? UITouch{
        let location:CGPoint = touch.locationInView(self.view!)
        start = location
        startTime = touch.timestamp
    }
}

override func touchesEnded(touches: Set<NSObject>, withEvent event: UIEvent) {
    if let touch:UITouch = touches.first as? UITouch{
        let location:CGPoint = touch.locationInView(self.view!)

        var dx:CGFloat = location.x - start!.x;
        var dy:CGFloat = location.y - start!.y;
        var magnitude:CGFloat = sqrt(dx*dx+dy*dy)

        if (magnitude >= kMinDistance) {
            // Determine time difference from start of the gesture
            var dt:CGFloat = CGFloat(touch.timestamp - startTime!)
            if (dt > kMinDuration) {
                // Determine gesture speed in points/sec
                var speed:CGFloat = magnitude / dt;
                if (speed >= kMinSpeed && speed <= kMaxSpeed) {
                    // Swipe detected
                }
            }
        }
    }
}

Honesty need to say that his has not been tested but I needed some code like this so this was converted on the go.

EDIT: Tested and seems to work with Swift 1.2
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