基本上我想做的是缓存单元格并让视频继续播放。当用户滚动回到单元格时，视频应该只从播放的位置显示。
问题是玩家被移除，并且单元格最终出现在随机单元格上，而不是其指定区域。
您需要有两个视频才能实现此功能，我从此处下载了这些视频 https://commondatastorage.googleapis.com/gtv-videos-bucket/sample/ElephantsDream.mp4 我刚刚用两个不同的名称保存了同一个视频两次。
如何重现问题: 点击第一个单元格，然后一直向下滚动，然后向上滚动，您会注意到视频开始出现在各处。我只想让视频出现在正确的位置，而不是出现在其他地方。
这里是代码的链接:Code link
class ViewController: UIViewController {
private var collectionView: UICollectionView!
private var videosURLs: [String] = [
"ElephantsDream2", "ElephantsDream", "ElephantsDream", "ElephantsDream", "ElephantsDream", "ElephantsDream", "ElephantsDream", "ElephantsDream", "ElephantsDream", "ElephantsDream", "ElephantsDream", "ElephantsDream", "ElephantsDream", "ElephantsDream",
"ElephantsDream", "ElephantsDream", "ElephantsDream", "ElephantsDream",
"ElephantsDream", "ElephantsDream", "ElephantsDream", "ElephantsDream",
"ElephantsDream", "ElephantsDream", "ElephantsDream", "ElephantsDream"
]
var cacheItem = [String: (cell: CustomCell, player: AVPlayer)]()
override func viewDidLoad() {
super.viewDidLoad()
setupCollectionView()
}
private func setupCollectionView() {
collectionView = UICollectionView(frame: .zero, collectionViewLayout: ColumnFlowLayout())
view.addSubview(collectionView)
collectionView.register(CustomCell.self, forCellWithReuseIdentifier: "cell")
collectionView.dataSource = self
collectionView.delegate = self
collectionView.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
collectionView.leadingAnchor.constraint(equalTo: view.leadingAnchor),
collectionView.trailingAnchor.constraint(equalTo: view.trailingAnchor),
collectionView.topAnchor.constraint(equalTo: view.safeAreaLayoutGuide.topAnchor),
collectionView.bottomAnchor.constraint(equalTo: view.safeAreaLayoutGuide.bottomAnchor),
])
}
}
extension ViewController: UICollectionViewDelegate {
func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
guard let cell = collectionView.cellForItem(at: indexPath) as? CustomCell else { return }
let item = videosURLs[indexPath.row]
let viewModel = PlayerViewModel(fileName: item)
cell.setupPlayerView(viewModel.player)
cacheItem[item] = (cell, viewModel.player)
}
}
extension ViewController: UICollectionViewDataSource {
func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
videosURLs.count
}
func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
let item = videosURLs[indexPath.row]
if let cachedItem = cacheItem[item], indexPath.row == 0 {
print(indexPath)
print(item)
cachedItem.cell.setUpFromCache(cachedItem.player)
return cachedItem.cell
} else {
guard let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "cell", for: indexPath) as? CustomCell else { return UICollectionViewCell() }
cell.contentView.backgroundColor = .orange
let url = Bundle.main.url(forResource: item, withExtension: "mp4")
cell.playerItem = AVPlayerItem(url: url!)
return cell
}
}
}
class CustomCell: UICollectionViewCell {
private var cancelBag: Set<AnyCancellable> = []
private(set) var playerView: PlayerView?
var playerItem: AVPlayerItem?
override var reuseIdentifier: String?{
"cell"
}
override init(frame: CGRect) {
super.init(frame: frame)
setupViews()
}
override func prepareForReuse() {
super.prepareForReuse()
playerView = nil
playerView?.removeFromSuperview()
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
private func setupViews() {
layer.cornerRadius = 8
clipsToBounds = true
}
func setUpFromCache(_ player: AVPlayer) {
playerView?.player = player
}
func setupPlayerView(_ player: AVPlayer) {
if self.playerView == nil {
self.playerView = PlayerView(player: player, gravity: .aspectFill)
contentView.addSubview(playerView!)
playerView?.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
playerView!.leadingAnchor.constraint(equalTo: contentView.leadingAnchor),
playerView!.trailingAnchor.constraint(equalTo: contentView.trailingAnchor),
playerView!.topAnchor.constraint(equalTo: contentView.topAnchor),
playerView!.bottomAnchor.constraint(equalTo: contentView.bottomAnchor)
])
playerView?.player?.play()
NotificationCenter.default.publisher(for: .AVPlayerItemDidPlayToEndTime).sink { [weak self] notification in
if let p = notification.object as? AVPlayerItem, p == player.currentItem {
self?.playerView?.removeFromSuperview()
guard let self = self else { return }
NotificationCenter.default.removeObserver(self, name: .AVPlayerItemDidPlayToEndTime, object: nil)
}
}.store(in: &cancelBag)
} else {
playerView?.player?.pause()
playerView?.removeFromSuperview()
playerView = nil
}
}
}
最佳答案
在尝试实现你想要的东西时，我会考虑/考虑改变一些事情，这可能是我们看到这种奇怪的细胞行为的原因:
处理 Collection View 时使用
indexPath.item而不是indexPath.row在您
prepareForReuse中，您实际上丢弃了playerView，因此当您尝试从缓存中再次恢复播放器时playerView?.player = player-playerView很可能为零，需要重新初始化您不需要将单元作为一个整体来保存，这可能会起作用，但是我认为我们应该让 Collection View 完成回收单元的业务。只保留玩家
我还没有这样做，但是，请考虑在丢弃单元格时如何处理删除通知观察者，因为您可能会多次订阅通知，这可能会导致问题
我也没有这样做，但请记住在视频结束时从缓存中删除视频，因为您不希望单元格再使用react
以下是我所做的一些小更改:
自定义单元格
// I made this code into a function since I figured we might reuse it
private func configurePlayerView(_ player: AVPlayer) {
self.playerView = PlayerView(player: player, gravity: .aspectFill)
contentView.addSubview(playerView!)
playerView?.translatesAutoresizingMaskIntoConstraints = false
NSLayoutConstraint.activate([
playerView!.leadingAnchor.constraint(equalTo: contentView.leadingAnchor),
playerView!.trailingAnchor.constraint(equalTo: contentView.trailingAnchor),
playerView!.topAnchor.constraint(equalTo: contentView.topAnchor),
playerView!.bottomAnchor.constraint(equalTo: contentView.bottomAnchor)
])
playerView?.player?.play()
NotificationCenter.default.publisher(for: .AVPlayerItemDidPlayToEndTime).sink { [weak self] notification in
if let p = notification.object as? AVPlayerItem, p == player.currentItem {
self?.playerView?.removeFromSuperview()
guard let self = self else { return }
NotificationCenter.default.removeObserver(self, name: .AVPlayerItemDidPlayToEndTime, object: nil)
}
}.store(in: &cancelBag)
}
func setUpFromCache(_ player: AVPlayer) {
// Check if the playerView needs to be set up
if playerView == nil {
configurePlayerView(player)
}
playerView?.player = player
}
func setupPlayerView(_ player: AVPlayer) {
// Replace the code from here and use the function
if self.playerView == nil {
configurePlayerView(player)
} else {
playerView?.player?.pause()
playerView?.removeFromSuperview()
playerView = nil
}
}
// No big change, this might have no impact, I changed the order
// of operations. You can use your previous code if it makes no difference
// but I added it for completeness
override func prepareForReuse() {
playerView?.removeFromSuperview()
playerView = nil
super.prepareForReuse()
}
ViewController
// I use the index path as a whole as the key
// I only store a reference to the player, not the cell
var cacheItem = [IndexPath: AVPlayer]()
// Some changes have to be made to made to support the new
// cache type
func collectionView(_ collectionView: UICollectionView,
didSelectItemAt indexPath: IndexPath) {
guard let cell
= collectionView.cellForItem(at: indexPath) as? CustomCell else { return }
let item = videosURLs[indexPath.item]
let viewModel = PlayerViewModel(fileName: item)
cell.setupPlayerView(viewModel.player)
cacheItem[indexPath] = (viewModel.player)
}
// I set up a regular cell here
func collectionView(_ collectionView: UICollectionView,
cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
guard let cell
= collectionView.dequeueReusableCell(withReuseIdentifier: "cell",
for: indexPath) as? CustomCell else { return UICollectionViewCell() }
let item = videosURLs[indexPath.row]
cell.contentView.backgroundColor = .orange
let url = Bundle.main.url(forResource: item, withExtension: "mp4")
cell.playerItem = AVPlayerItem(url: url!)
return cell
}
// I manage restoring an already playing cell here
func collectionView(_ collectionView: UICollectionView,
willDisplay cell: UICollectionViewCell,
forItemAt indexPath: IndexPath)
{
if let cachedItem = cacheItem[indexPath],
let cell = cell as? CustomCell
{
print("playing")
print(indexPath)
print(cachedItem)
cell.setUpFromCache(cachedItem)
}
}
经过这些更改，我想你会得到你想要的:
关于swift - 如何缓存单元格并在每个单元格中嵌入了 avplayer 的 Collection View 中重用单元格？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/71459442/