 
 import UIKit
 
-class DropItViewController: UIViewController {
+class DropItViewController: UIViewController, UIDynamicAnimatorDelegate {
 
     @IBOutlet weak var gameView: UIView!
     

    // Do not call this before self.gameView is set
    lazy var animator: UIDynamicAnimator = {
       let lazilyCreatedDynamicAnimator = UIDynamicAnimator(referenceView: self.gameView)
        return lazilyCreatedDynamicAnimator
    }()
    

    override func viewDidLoad() {
        super.viewDidLoad()
        animator.addBehavior(dropitBehavior)
    }
    
    func dynamicAnimatorDidPause(animator: UIDynamicAnimator) {
        removeCompletedRow()
    }
    @IBAction func drop(sender: UITapGestureRecognizer) {
        drop()
