avplayer - iOS12下视频无法正常播放

Question

我正在使用 AVAssetResourceLoader 加载数据和 AVPlayerViewController 来播放。它在iOS10、11下可以正常工作，但在iOS12下就不行了。播放时，进程条向前移动，但视频只播放1秒，一直卡到最后。

这是我的 AVAssetResourceLoader 代码：

  class MediaResourceLoader: NSObject, AVAssetResourceLoaderDelegate {
    func resourceLoader(
        _ resourceLoader: AVAssetResourceLoader,
        shouldWaitForLoadingOfRequestedResource loadingRequest: AVAssetResourceLoadingRequest
    ) -> Bool {
      loadingRequest.contentInformationRequest?.contentType = kUTTypeMPEG4 as String
      loadingRequest.contentInformationRequest?.contentLength = Int64(self.data.count)
      loadingRequest.contentInformationRequest?.isByteRangeAccessSupported = true

      guard let request = loadingRequest.dataRequest else { return false }
      if request.requestsAllDataToEndOfResource {
        request.respond(with: data)
      } else if Int(request.requestedOffset) <= request.requestedLength {
        let subData = self.data.subdata(in: Int(request.requestedOffset)..<request.requestedLength)
        request.respond(with: subData)
      }

      loadingRequest.finishLoading()

      return true
    }
 }