     // Mark: - UIPresentationController
     override var frameOfPresentedViewInContainerView: CGRect {
         if let unWrappedContainerView = self.containerView {
-            return CGRect(origin: self.configureModel.preferredOriginPoint(from: unWrappedContainerView)
-                          , size: self.configureModel.preferredSize)
+            if let unWrappedConfigureModel = self.configureModel {
+                return CGRect(origin: unWrappedConfigureModel.preferredOriginPoint(from: unWrappedContainerView)
+                              , size: unWrappedConfigureModel.preferredSize)
+            } else {
+                return unWrappedContainerView.bounds
+            }
         } else {
             return CGRect.zero
         }

        self.dimmingView.addSubview(self.presentedViewController.view)
        self.presentedViewController.transitionCoordinator?.animate(alongsideTransition: { [unowned self] (_) in
            self.dimmingView.alpha = 1
            if self.configureModel.shouldShrinkPresentingViewController {
                self.presentingViewController.view.transform = CGAffineTransform(scaleX: 0.9, y: 0.9)
            }
        }, completion: nil)


fileprivate class UNDSideSlidePresentationController: UIPresentationController {
    
    var configureModel: UNDSideSlideTransitioningConfigModel?
    var dimmingView: UIView!
    var panGestureRecognizer: UIPanGestureRecognizer?
    var dismissTapGestureRecognizer: UITapGestureRecognizer?
