         
         if isExplicityScrolling {
             leftSidePageIndex = Int(scrollView.contentOffset.x / scrollView.bounds.width)
-            delegate?.contentViewController(viewController: self, didEndManualScrollOn: leftSidePageIndex)
+            delegate?.contentViewController?(viewController: self, didEndManualScrollOn: leftSidePageIndex)
         }
         isExplicityScrolling = false
         loadPagesIfNeeded()

    public func scrollViewDidEndDecelerating(_ scrollView: UIScrollView) {
        if isExplicityScrolling {
            leftSidePageIndex = Int(scrollView.contentOffset.x / scrollView.bounds.width)
            delegate?.contentViewController(viewController: self, didEndManualScrollOn: leftSidePageIndex)
        }
        isExplicityScrolling = false
        loadPagesIfNeeded()

            vc?.view.frame = scrollView.bounds
            vc?.view.frame.origin.x = scrollView.bounds.width * CGFloat(offset)
        }
    }
    
    override public func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }

    override public func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
        removeAll()
        initialLoad(with: leftSidePageIndex)
        coordinator.animate(alongsideTransition: { [weak self] (context) in
            guard let _self = self else { return }
            _self.scroll(to: _self.leftSidePageIndex, animated: false)
        }, completion: nil)
        
        super.viewWillTransition(to: size, with: coordinator)
    }
