import UIKit

    class ViewController: UIViewController {

    @IBOutlet weak var mainImageView: UIImageView!    //Background Image
    var Person: UIImageView!         //Foreground Image
    var location = CGPoint(x: 0, y: 0)
    var image: UIImage!
    var frontSize: CGSize!

    @IBOutlet weak var overlayButton: UIButton!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        let image: UIImage = UIImage(named: "pizza")!
        frontSize = image.size
        Person = UIImageView(frame: CGRectMake(90, 140, image.size.width, image.size.height))
        Person.image = image
        Person.contentMode = .ScaleAspectFit

        Person.userInteractionEnabled = true

        self.mainImageView.addSubview(Person)

    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }

    override func viewWillAppear(animated: Bool) {
        super.viewWillAppear(animated)


    }

    override func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?) {
        if (segue.identifier == "detailImage") {
            let imageVC = (segue.destinationViewController as! ImageViewController)

            imageVC.image = image
        }
    }

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

        let touch : UITouch! = event.allTouches()?.first

        location = touch.locationInView(self.mainImageView)

        Person.center = location

    }

    override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent!) {

        let touch : UITouch! = event.allTouches()?.first

        location = touch.locationInView(self.mainImageView)

        Person.center = location

    }

    override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) {
        let size = CGSizeMake(mainImageView.image!.size.width, mainImageView.image!.size.height)
        UIGraphicsBeginImageContextWithOptions(size, false, 0.0)

        mainImageView.image?.drawInRect(CGRectMake(mainImageView.frame.origin.x, mainImageView.frame.origin.y, size.width, size.height))
        Person.image?.drawInRect(CGRectMake(location.x, location.y, frontSize.width, frontSize.height))

        let newImage:UIImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        //set finalImage to IBOulet UIImageView
        image = newImage

    }

}