     }
     
     // MARK: - UICollectionViewDataSource
-
+    
     func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
         return self.viewControllers.count
     }

        nextCell?.titleLabel?.textColor = self.titleColorNormal.transFormColorTo(self.titleColorSelected, progress: progress)
        
        //update size or font

        if isZoomTitle {
            let currentItemScale = maxItemScale - (maxItemScale - 1) * progress
            let nextItemScale = 1 + (maxItemScale - 1) * progress

        if progress == 0 {
            progress = 1
        }
        
        //get next index
        var nextIndex = index
        if scrollView.contentOffset.x > scrollView.bounds.width * CGFloat(index) {
