Ios AVAssetResourceLoaderDelegate不回叫AVplayer

我正在尝试设置一个渐进的视频下载，从服务器URL流。我能够调用AVAssetResourceLoaderDelegate，首先是信息请求，然后是数据请求，它获取前1000字节的数据。但是，代理从不回电话并启动播放机。我逐字节检查了数据，结果是正确的

-(void)videoCallingMethod {
    NSURL *url = [NSURL URLWithString:@"fakeurl://mypath.com/moviefile.mp4"];

    dispatch_queue_t serialQueue = dispatch_queue_create("com.meels.queue", DISPATCH_QUEUE_SERIAL);
        dispatch_async(serialQueue, ^{
            _asset = [[AVURLAsset alloc] initWithURL:url options:nil];    
            [_asset.resourceLoader setDelegate:self queue:serialQueue];

            _playerItem = [AVPlayerItem playerItemWithAsset:_asset];
            _player = [AVPlayer playerWithPlayerItem:_playerItem]; // This will call the delegate        

            _playerLayer = [AVPlayerLayer playerLayerWithPlayer:_player];
            [_playerLayer setFrame:self.view.frame];
            [self.view.layer addSublayer:_playerLayer];
            [_player play];
    });
}

- (BOOL)resourceLoader:(AVAssetResourceLoader *)resourceLoader shouldWaitForLoadingOfRequestedResource:(AVAssetResourceLoadingRequest *)loadingRequest {

    BOOL returnValue = FALSE;
    if(loadingRequest.contentInformationRequest) {

        loadingRequest.contentInformationRequest.contentType = @"public.mpeg-4";  // "public.mpeg-4" "kUTTypeMPEG4"
        loadingRequest.contentInformationRequest.contentLength = 1000;
        loadingRequest.contentInformationRequest.byteRangeAccessSupported = YES;

        NSLog(@"contentInformationRequest loadingRequest %@", loadingRequest);
        [loadingRequest finishLoading]; // This will trigger the data request   
        returnValue = TRUE;

    } else if(loadingRequest.dataRequest) {
        NSLog(@"It's a dataRequest");

        // Here the url custom scheme is removed and the url changed back to http to point to the exact url location where my file is
        NSURLComponents *urlComponents = [NSURLComponents componentsWithURL:loadingRequest.request.URL resolvingAgainstBaseURL:NO];
        urlComponents.scheme = @"http";
        NSMutableURLRequest *mutableLoadingRequest = [loadingRequest.request mutableCopy];
        [mutableLoadingRequest setURL:urlComponents.URL];

        NSURLSession *session = [[NSURLSession alloc] init];
        NSURLSessionConfiguration *config = [NSURLSessionConfiguration defaultSessionConfiguration];
        session = [NSURLSession sessionWithConfiguration:config delegate:self delegateQueue:[NSOperationQueue mainQueue]];
        [[session dataTaskWithRequest:mutableLoadingRequest completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) {
            NSLog(@"Session block complete with error %@", error);

            if (error != nil) {
                NSLog(@"Error, %@", error);
            } else {
                NSLog(@"Response: %@",response); // status code: 206
                NSLog(@"data: %@",data);         // The data is correct
                if (data != nil) {
                    NSLog(@"Completing the request: %@", loadingRequest.dataRequest);
                    [loadingRequest.dataRequest respondWithData:data];
                    [loadingRequest finishLoading];     
                }
            }  
      }] resume];

      returnValue = TRUE;
    }
    return returnValue;
}

当我调用

[LoadingRequestFinishLoading]时

我希望代理将数据传递回

资源加载程序

，播放器开始播放，但这不会发生

委托已完成，没有任何错误。我检查了数据，结果是正确的。服务器以状态代码206作出响应。我试着以不同的格式使用MIME和UTI。它不影响响应。此外，如果禁用委托并恢复http url方案，视频将加载并播放良好。因此，文件本身没有问题