dragging images around the screen using swift

class DraggableImageView: UIImageView {


var dragStartPositionRelativeToCenter : CGPoint?

override init(image: UIImage!) {
    super.init(image: image)

    self.userInteractionEnabled = true   //< w00000t!!!1

    addGestureRecognizer(UIPanGestureRecognizer(target: self, action: "handlePan:"))

    layer.shadowColor = UIColor.blackColor().CGColor
    layer.shadowOffset = CGSize(width: 0, height: 3)
    layer.shadowOpacity = 0.5
    layer.shadowRadius = 2
}

required init?(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
}

func handlePan(nizer: UIPanGestureRecognizer!) {
    if nizer.state == UIGestureRecognizerState.Began {
        let locationInView = nizer.locationInView(superview)
        dragStartPositionRelativeToCenter = CGPoint(x: locationInView.x - center.x, y: locationInView.y - center.y)

        layer.shadowOffset = CGSize(width: 0, height: 20)
        layer.shadowOpacity = 0.3
        layer.shadowRadius = 6

        return
    }

    if nizer.state == UIGestureRecognizerState.Ended {
        dragStartPositionRelativeToCenter = nil

        layer.shadowOffset = CGSize(width: 0, height: 3)
        layer.shadowOpacity = 0.5
        layer.shadowRadius = 2

        return
    }

    let locationInView = nizer.locationInView(superview)

    UIView.animateWithDuration(0.1) {
        self.center = CGPoint(x: locationInView.x - self.dragStartPositionRelativeToCenter!.x,
            y: locationInView.y - self.dragStartPositionRelativeToCenter!.y)
    }
}

/*
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
override func drawRect(rect: CGRect) {
// Drawing code
}
*/   
}

Auto Layout is running a putting your images back to where the constraints say they should be.

The easiest way to get around this is to create your images in code instead of creating them in the Storyboard.

Something like:

let lightBulb = UIImageView(frame: CGRectMake(100, 100, 50, 50))
lightBulb.image = UIImage(named: "lightBulb")
lightBulb.contentMode = .ScaleToFill
lightBulb.userInteractionEnabled = true

lightBulb.addGestureRecognizer(UIPanGestureRecognizer(target: self, action: "handlePan:"))

self.view.addSubview(lightBulb)