Question

我已经按照here给出的教程进行HLS缓存，但控件永远不会到达任何代理（AVAssetDownloadDelegate）。

我错过了什么吗？这是我写的代码

- (void)setupAssetDownloader {
    NSURL *assetURL = [NSURL URLWithString:@"STREAMING_HOST/video/hls/3729170.m3u8"];
    AVURLAsset *hlsAsset = [AVURLAsset assetWithURL:assetURL];

    urlSessionConfiguration = [NSURLSessionConfiguration backgroundSessionConfigurationWithIdentifier:@"assetDowloadConfigIdentifier"];
    avAssetDownloadSession = [AVAssetDownloadURLSession sessionWithConfiguration:urlSessionConfiguration assetDownloadDelegate:self delegateQueue:[NSOperationQueue mainQueue]];

    // Download movie
    avAssetDownloadTask = [avAssetDownloadSession assetDownloadTaskWithURLAsset:hlsAsset assetTitle:@"downloadedMedia" assetArtworkData:nil options:nil];

//@{AVAssetDownloadTaskMinimumRequiredMediaBitrateKey : @(300000)}


    [avAssetDownloadTask resume];

    AVPlayerItem *playerItem = [[AVPlayerItem alloc] initWithAsset:avAssetDownloadTask.URLAsset];
    AVPlayer *player = [[AVPlayer alloc ] initWithPlayerItem:playerItem];
    AVPlayerLayer *playerLayer = [[AVPlayerLayer alloc ] init];
    [playerLayer setPlayer:player];
    [playerLayer setFrame:self.view.frame];
    [self.view.layer addSublayer:playerLayer];
    [player play];
}

#pragma mark - AVAssetDownloadDelegate

- (void)URLSession:(NSURLSession *)session assetDownloadTask:(AVAssetDownloadTask *)assetDownloadTask didResolveMediaSelection:(AVMediaSelection *)resolvedMediaSelection {

}
- (void)URLSession:(NSURLSession *)session assetDownloadTask:(AVAssetDownloadTask *)assetDownloadTask didLoadTimeRange:(CMTimeRange)timeRange totalTimeRangesLoaded:(NSArray<NSValue *> *)loadedTimeRanges timeRangeExpectedToLoad:(CMTimeRange)timeRangeExpectedToLoad {
    NSInteger percent = 0;
    for (NSValue *value in loadedTimeRanges) {
        CMTimeRange timeRange = [value CMTimeRangeValue];
        percent += CMTimeGetSeconds(timeRange.duration) / CMTimeGetSeconds(timeRangeExpectedToLoad.duration);
    }
    percent *= 100;
    NSLog(@"Progress: %ld", (long)percent);
}

- (void)URLSession:(NSURLSession *)session assetDownloadTask:(AVAssetDownloadTask *)assetDownloadTask didFinishDownloadingToURL:(NSURL *)location {
    NSString *localPath = location.relativePath;
    NSLog(@"localPath: %@", localPath);
    // TODO: Play downloaded file
    // IMPORTANT: Don't move this file to another location.
}

Answer 1

我在模拟器上运行代码和

模拟器上不支持下载HLS流。

当我使用下面提到的委托方法时，我想出来了。

- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error {

}

现在挣扎了一整天，我找到了Apple here的一个样本，并找到了问题背后的真正原因。

Answer 2

我最近遇到了同样的症状。

原来我的应用中有另一个设置后台 URL 会话的对象。

let configuration = URLSessionConfiguration.background(withIdentifier: "[id]")

一旦我删除了另一个会话，我就开始收到预期的回调。

也许某处记录了应用程序不应设置多个后台下载会话，但无论如何这解决了我的问题。

用于HLS缓存的AVAssetDownloadDelegate方法未被调用

2 个答案: