                     
                     if (self.selectedViewController != nil) {
                         self.delegate?.em_pageViewController?(self, isScrollingFrom: self.selectedViewController!, destinationViewController: self.beforeViewController!, progress: progress)
+                    }
+                } else {
+                    if (self.selectedViewController != nil) {
+                        self.delegate?.em_pageViewController?(self,
+                                                              isScrollingFrom: self.selectedViewController!,
+                                                              destinationViewController: nil,
+                                                              progress: progress)
                     }
                 }
                 

    
    private func loadBeforeViewController(for selectedViewController:UIViewController) {
        // Retreive the new before controller from the data source if available, otherwise set as nil
        self.beforeViewController = self.dataSource?.em_pageViewController(self, viewControllerBeforeViewController: selectedViewController)
    }
    
    private func loadAfterViewController(for selectedViewController:UIViewController) {
        // Retreive the new after controller from the data source if available, otherwise set as nil
        self.afterViewController = self.dataSource?.em_pageViewController(self, viewControllerAfterViewController: selectedViewController)
    }
    
    

     - parameter destinationViewController: The view controller being scrolled to where the transition should end
     - parameter progress: The progress of the transition, where 0 is a neutral scroll position, >= 1 is a complete transition to the right view controller in a horizontal orientation, or the below view controller in a vertical orientation, and <= -1 is a complete transition to the left view controller in a horizontal orientation, or the above view controller in a vertical orientation. Values may be greater than 1 or less than -1 if bouncing is enabled and the scroll velocity is quick enough.
     */
    @objc optional func em_pageViewController(_ pageViewController: EMPageViewController, isScrollingFrom startingViewController: UIViewController, destinationViewController:UIViewController?, progress: CGFloat)
    
    /**
     Called after a page transition attempt has completed.
