UICollectionView自动滚动会跳过一个项目

Question

我正在尝试使用UICollectionView构建像Instagram Stories这样的功能。我已为“集合”视图禁用了UserInteraction，但是在使用collectionView.scrollToItem时，CollectionView会跳过一个单元格。这是我的代码。这可能是什么问题？

func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        let screenSize = UIScreen.main.bounds.size
        return screenSize
    }


    private var playbackLikelyToKeepUpContext = 0
    private var currentIndexPath: IndexPath?

    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        if let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "storiesCell", for: indexPath) as? StoriesCell {
            let currentContent = allVideoUrls[indexPath.item]
            currentIndexPath = indexPath
            Logger.print(currentIndexPath!.item)
            if let url = URL(string: currentContent) {
                let playerItem:AVPlayerItem = AVPlayerItem(url: url)
                player = AVPlayer(playerItem: playerItem)


                let playerLayer=AVPlayerLayer(player: player!)
                playerLayer.frame=CGRect(x:0, y:0, width:self.view.bounds.width, height:self.view.bounds.height)
                cell.layer.addSublayer(playerLayer)
                self.view.layer.addSublayer(playerLayer)
                storiesCollectionView.isScrollEnabled = false
                player!.addObserver(self, forKeyPath: "currentItem.playbackLikelyToKeepUp",
                                        options: .new, context: &playbackLikelyToKeepUpContext)
                NotificationCenter.default.addObserver(self, selector: #selector(playerItemDidReachEnd), name: NSNotification.Name.AVPlayerItemDidPlayToEndTime, object: nil) // Add observer


                return cell
            }

        }
        return UICollectionViewCell()
    }

    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        if context == &playbackLikelyToKeepUpContext && player != nil{
            Logger.print(currentIndexPath)
            if player!.currentItem != nil {
                if player!.currentItem!.isPlaybackLikelyToKeepUp {
                    player!.play()
                    // loadingIndicatorView.stopAnimating() or something else
                } else {
                    // loadingIndicatorView.startAnimating() or something else
                }
            }

        }
    }

    @objc func playerItemDidReachEnd(notification: NSNotification) {
        if currentIndexPath != nil {
            let currentRow = currentIndexPath!.item
            let nextItem = currentIndexPath!.item + 1
            player = nil
            if currentRow < allVideoUrls.count {
                Logger.print("Next: \(nextItem)")
                let nextIndexPath = IndexPath(item: nextItem, section: 0)
                DispatchQueue.main.asyncAfter(deadline: .now() + 0.35) {
                    self.storiesCollectionView.scrollToItem(at: nextIndexPath, at: [.centeredVertically, .centeredHorizontally], animated: true)
                }


            }

        }

    }