         var collectionViewCell: UICollectionViewCell
         
         if indexPath.section == 0 {
-            let asset = self.assetsFetchResults![(indexPath as NSIndexPath).item] as! PHAsset
+            let asset = self.assetsFetchResults![indexPath.item] as! PHAsset
             let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "GirdViewCell", for: indexPath) as! GirdViewCell
             cell.representedAssetIdentifier = asset.localIdentifier
             self.imageManager?.requestImage(for: asset, targetSize: AssetGirdThumbnailSize!, contentMode: .aspectFill, options: nil, resultHandler: { (image, info) in

        if let _ = assetCollection {
            self.navigationItem.rightBarButtonItem = UIBarButtonItem(barButtonSystemItem: .add, target: self, action: #selector(addVideo))
        }
        // 注册通知
        NotificationCenter.default.addObserver(self, selector: #selector(downloadFinished), name: VideoMarksConstants.DownloadTaskFinish, object: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(downloading), name: VideoMarksConstants.DownloadTaskProgress, object: nil)

    var imageManager: PHCachingImageManager?
    var previousPreheatRect: CGRect?
    var taskManager = TaskManager.sharedInstance
    var longTapGuesture: UILongPressGestureRecognizer?

    override func awakeFromNib() {
        self.setupViews()
