视频无法在iOS12下正常播放

Question

我正在使用AVAssetResourceLoader加载数据并使用AVPlayerViewController进行播放。 它在iOS10、11下正常工作，但在iOS12下不再工作。 播放时，进度条会向前移动，但是视频只能播放1秒，并且一直停留到结束。

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
    }
 }