我正在iOS中创建一个下载M3u8文件的功能。我可以下载M3u8,但我希望能够在应用暂停或退出时恢复待下载的功能。以下是我使用的主要文档,但我无法让还原功能按照预期工作。
下面是我用来下载M3U8的方法。
private var config: URLSessionConfiguration!
var downloadSession: AVAssetDownloadURLSession!
var downloadTask: AVAssetDownloadTask!
var mediaSelectionMap = [AVAssetDownloadTask : AVMediaSelection]()
let downloadIdentifier = "mySession"
func assetDownload(url: URL) {
print("Download started...")
//Create new background session configuration
let configuration = URLSessionConfiguration.background(withIdentifier: downloadIdentifier)
//Create a new AVAssetDownloadURLSession with background config, delegate and queue
let downloadSession = AVAssetDownloadURLSession(configuration: configuration, assetDownloadDelegate: self, delegateQueue: OperationQueue.main)
downloadSession.getAllTasks { (taskArray) in
//Task array always nil when segment should be found
if taskArray.count > 0 {
print("Check if to resume previous download")
self.restorePendingDownloads()
} else {
let asset = AVURLAsset(url: url)
print("New Movie downloading")
//Create new AVAssetDownloadTask for the desired asset
self.downloadTask = downloadSession.makeAssetDownloadTask(asset: asset, assetTitle: "VideoSample", assetArtworkData: nil, options: [AVAssetDownloadTaskMinimumRequiredMediaBitrateKey: NSNumber(value: 0)])
//Start task and begin download
self.downloadTask?.resume()
}
}
}
下面是还原待定功能
func restorePendingDownloads() {
print("restore pending download...")
// Create session configuration with ORIGINAL download identifier
config = URLSessionConfiguration.background(withIdentifier: downloadIdentifier)
// Create a new AVAssetDownloadURLSession
downloadSession = AVAssetDownloadURLSession(configuration: config,
assetDownloadDelegate: self,
delegateQueue: OperationQueue.main)
// Grab all the pending tasks associated with the downloadSession
downloadSession.getAllTasks { tasksArray in
print("getting all tasks.. \(tasksArray.count)") //returns 0
// For each task, restore the state in the app
for task in tasksArray {
guard let downloadTask = task as? AVAssetDownloadTask else { break }
// Restore asset, progress indicators, state, etc...
let asset = downloadTask.urlAsset
print("asset:\(asset)")
//NEVER CALLED BECAUSE EMPTY
}
}
}
有人推荐使用下面的功能,但这只是将下载重置到起点。
func restorePendingDownload(url: URL){
let urlAsset = AVURLAsset(url: url)
downloadTask = downloadSession.makeAssetDownloadTask(asset: urlAsset, assetTitle: "master", assetArtworkData: nil, options: nil)
downloadTask.resume()
}
更新
我找到了暂停恢复功能的解决方案,但没有找到应用退出时如何恢复的解决方案。
我添加了这个函数,它可以存储暂停时的 destinationURL,并且可以在还原待定函数中使用。
func urlSession(_ session: URLSession, assetDownloadTask: AVAssetDownloadTask, didFinishDownloadingTo location: URL) {
// Do not move the asset from the download location
UserDefaults.standard.set(location.relativePath, forKey: "assetPath")
destinationURL = location
}
在donwload asset函数中,我把下面一行从。
self.downloadTask = downloadSession.makeAssetDownloadTask(asset: asset, assetTitle: "VideoSample", assetArtworkData: nil, options: [AVAssetDownloadTaskMinimumRequiredMediaBitrateKey: NSNumber(value: 0)])
改为:
self.downloadTask = downloadSession.makeAssetDownloadTask(asset: asset, assetTitle: "VideoSample", assetArtworkData: nil, options: nil)
我想是设置最低要求导致了这个问题。
任何帮助或指导如何在退出应用程序时恢复待下载将是惊人的。谢谢你的帮助
从HLSCatalog的例子中,我试着在创建AVAssetDownloadTask时将[AVAssetDownloadTaskMinimumRequiredMediaBitrateKey: 265_000]添加到选项中。
在AppDelegate中,我调用 restorePending(),getAllTasks返回待处理任务的数量。在下一步,我仍然得到错误,我还在解决,但任务不是空的。
希望对你有所帮助。