         layoutItemViews()
     }
     
-    // TODO: change name now that view can be nil
-    private func viewDidPanHorizontally(view: UIView?, byOffset offset: CGFloat) {
+    private func didPanHorizontally(byOffset offset: CGFloat, forView view: UIView? = nil) {
         // TODO: clean this up
         
         // Calculate the new x origin point for the view that was panned.

                velocityX += force * timeDelta
                let offset = velocityX * timeDelta
                
                self.viewDidPanHorizontally(nil, byOffset: CGFloat(offset))
                
                print("force: \(force), time: \(timeDelta), offset: \(offset), speed: \(velocityX)")


    var animator: UIDynamicAnimator?
    
    func viewWasPanned(recognizer: UIPanGestureRecognizer) {
        switch recognizer.state {
        case .Possible, .Began:
            decelerateDisplayLinkProgressor = nil
