问m3u8未离线播放- swift 3.0

EN

func setupAssetDownload() {
        // Create new background session configuration.
         configuration = URLSessionConfiguration.background(withIdentifier: DOWNLOAD_ID)

        // Create a new AVAssetDownloadURLSession with background configuration, delegate, and queue
         downloadSession = AVAssetDownloadURLSession(configuration: configuration,
                                                    assetDownloadDelegate: self,
                                                    delegateQueue: OperationQueue.main)
        let url = URL(string: urlString)
        let asset = AVURLAsset(url: url!)


        // Create new AVAssetDownloadTask for the desired asset
        let downloadTask = downloadSession.makeAssetDownloadTask(asset: asset, assetTitle: "asset_Title", assetArtworkData: nil, options: nil)
        // Start task and begin download
        downloadTask?.resume()

    }

let DOWNLOAD_ID = "downloadIdentifier"

let urlString = "http://domain/vod/mp4:sample1.mp4/playlist.m3u8"

// Saving the Download Location

    func urlSession(_ session: URLSession, assetDownloadTask: AVAssetDownloadTask, didFinishDownloadingTo location: URL) {


        print("didFinishDownloadingTo \(location.relativePath)")
        // Do not move the asset from the download location
        UserDefaults.standard.set(location.relativePath, forKey: "assetPath")
    }

<AVURLAsset: 0x1742319e0, URL = file:///var/mobile/Containers/Data/Application/79C0043F-6161-4231-9129-B71C95903E05/Library/com.apple.UserManagedAssets.bhVNRN/asset_Title_63128673BE57FBDD.movpkg/>

func playOfflineAsset() {
        guard let assetPath = UserDefaults.standard.value(forKey: "assetPath") as? String else {
            // Present Error: No offline version of this asset available
            return
        }
        let baseURL = URL(fileURLWithPath: NSHomeDirectory())
        let assetURL = baseURL.appendingPathComponent(assetPath)
        let asset = AVURLAsset(url: assetURL)


        let player = AVPlayer(url:assetURL)

        let playerLayer = AVPlayerLayer(player: player)
        playerLayer.frame = videoView2.bounds
        playerLayer.backgroundColor = UIColor.purple.cgColor
        videoView2.layer.addSublayer(playerLayer)

        player.play()


        if let cache = asset.assetCache, cache.isPlayableOffline {
            // Set up player item and player and begin playback

            print("exist")

        } else {
            // Present Error: No playable version of this asset exists offline
            print("doesn't exist")
        }
    }