Discover how to download and play HLS offline

2:52 - AVAssetDownloadTask

let hlsAsset = AVURLAsset(url: assetURL)

let backgroundConfiguration = URLSessionConfiguration.background(
    withIdentifier: "assetDownloadConfigurationIdentifier")
let assetURLSession = AVAssetDownloadURLSession(configuration: backgroundConfiguration,
    assetDownloadDelegate: self, delegateQueue: OperationQueue.main())

// Download a Movie at 2 mbps
let assetDownloadTask = assetURLSession.makeAssetDownloadTask(asset: hlsAsset,
    assetTitle: "My Movie", assetArtworkData: myAssetArtwork,
    options: [AVAssetDownloadTaskMinimumRequiredMediaBitrateKey: 2000000])!
assetDownloadTask.resume()



// AVAssetDownloadTask uses automatic media selection

3:41 - Monitor AVAssetDownloadTask

// Monitor AVAssetDownloadTask
public protocol AVAssetDownloadDelegate: URLSessionTaskDelegate {


	// Use to monitor progress
	func urlSession(_ session: URLSession, assetDownloadTask: AVAssetDownloadTask,
		didLoad timeRange: CMTimeRange, totalTimeRangesLoaded loadedTimeRanges: [NSValue],
		timeRangeExpectedToLoad: CMTimeRange)


	// Listen for completion
	func urlSession(_ session: URLSession, task: URLSessionTask,
		didCompleteWithError error: Error?)

}

4:10 - Monitoring example

// Monitoring
MyAssetDownloadDelegate: NSObject, AVAssetDownloadDelegate {
    func urlSession(_ session: URLSession, assetDownloadTask: AVAssetDownloadTask,
didLoad timeRange: CMTimeRange, totalTimeRangesLoaded loadedTimeRanges: [NSValue], timeRangeExpectedToLoad: CMTimeRange) {

		// Convert loadedTimeRanges to CMTimeRanges
		var percentComplete = 0.0
		for value in loadedTimeRanges {
			let loadedTimeRange: CMTimeRange = value.timeRangeValue 
			percentComplete += CMTimeGetSeconds(loadedTimeRange.duration) /
				CMTimeGetSeconds(timeRangeExpectedToLoad.duration)
		}
		percentComplete *= 100
		print("percent complete: \(percentComplete)")
	}
}

4:55 - Choose media-selections

let hlsAsset = AVURLAsset(url: assetURL)
let myMediaSelections = [] // audio media-selections followed by subtitle media-selections

guard hlsAsset.statusOfValue(forKey: "availableMediaCharacteristicsWithMediaSelectionOptions", error: nil) 
   == AVKeyValueStatus.loaded else { return }

let mediaCharacteristic = //AVMediaCharacteristic.audible or AVMediaCharacteristic.legible
let mediaSelectionGroup = hlsAsset.mediaSelectionGroup(forMediaCharacteristic: mediaCharacteristic)
if let options = mediaSelectionGroup?.options {
    for option in options {
        // chose your media selection option
        if /* this is my option */ {
            let mutableMediaSelection = hlsAsset.preferredMediaSelection.mutableCopy()
            mutableMediaSelection.select(option, in: mediaSelectionGroup)
            myMediaSelections.append(mutableMediaSelection)
        }
    }
}

5:11 - AVAggregateAssetDownloadTask

let hlsAsset = AVURLAsset(url: assetURL)
let myMediaSelections = ...

let backgroundConfiguration = URLSessionConfiguration.background(
    withIdentifier: "assetDownloadConfigurationIdentifier")
let assetURLSession = AVAssetDownloadURLSession(configuration: backgroundConfiguration,
    assetDownloadDelegate: self, delegateQueue: OperationQueue.main())

// Download a Movie at 2 mbps
let aggDownloadTask = assetURLSession.aggregateAssetDownloadTask(with: hlsAsset,
    mediaSelections: myMediaSelections,
    assetTitle: "My Movie",
    assetArtworkData: myAssetArtwork,
    options:[AVAssetDownloadTaskMinimumRequiredMediaBitrateKey: 2000000])!
aggDownloadTask.resume()

6:31 - Monitor AVAggregateAssetDownloadTask

// Monitor AVAggregateAssetDownloadTask
public protocol AVAssetDownloadDelegate: URLSessionTaskDelegate {

	// Use to monitor progress
	func urlSession(_ session: URLSession, 
		aggregateAssetDownloadTask: AVAggregateAssetDownloadTask, 
		didLoad timeRange: CMTimeRange, totalTimeRangesLoaded loadedTimeRanges: [NSValue], 
		timeRangeExpectedToLoad: CMTimeRange, 
		for mediaSelection: AVMediaSelection
	)

	// Listen for completion for each media selection
	func urlSession(_ session: URLSession, 
		aggregateAssetDownloadTask: AVAggregateAssetDownloadTask, 
		didCompleteFor mediaSelection: AVMediaSelection)

    // In case of audio rendition, expect calls once for stereo followed by once for multichannel rep.
}

7:04 - Restore Tasks on App Launch

// Restore Tasks on App Launch
class MyAppDelegate: UIResponder, UIApplicationDelegate {
	func application(_ application: UIApplication, 
			didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
		let configuration = URLSessionConfiguration.background(withIdentifier:
			"assetDownloadConfigurationIdentifier")
		let session = URLSession(configuration: configuration) 
		session.getAllTasks { tasks in
			for task in tasks {
				if let assetDownloadTask = task as? AVAssetDownloadTask {
					// restore progress indicators, state, etc...
				} 
			}
		}
	}
}

7:44 - Store the download location

// Store the download location
public protocol AVAssetDownloadDelegate: URLSessionTaskDelegate {

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

	// AVAggregateAssetDownloadTask
	func urlSession(_ session: URLSession, 
		aggregateAssetDownloadTask: AVAggregateAssetDownloadTask, 
		willDownloadTo location: URL)

}

8:05 - Instantiating Your AVAsset for Playback

// Instantiating Your AVAsset for Playback

// 1) Create Asset for AVAssetDownloadTask
let networkURL = URL(string: "http://example.com/master.m3u8")!
let asset = AVURLAsset(url: networkURL)
let task = assetDownloadSession.makeAssetDownloadTask(asset: asset, assetTitle: "My Movie",
assetArtworkData: nil, options: nil)


// 2) Re-use Asset for Playback, Even After Task Restoration at App Launch
let playerItem = AVPlayerItem(asset: task.urlAsset)


// Reusing asset, will allow AVFoundation to optimize resources between playback and download in cases where the playback happens before the download is complete.

8:56 - Create using file URL

// Create using file URL

let fileURL = URL(fileURLWithPath: self.savedAssetDownloadLocation)
let asset = AVURLAsset(url: fileURL)

let playerItem = AVPlayerItem(asset: task.urlAsset)

9:16 - What can I play offline?

// What can I play offline?

public class AVURLAsset {

	public var assetCache: AVAssetCache? { get }

}

public class AVAssetCache {

	public var isPlayableOffline: Bool { get }

	public func mediaSelectionOptions(in mediaSelectionGroup: AVMediaSelectionGroup)
		-> [AVMediaSelectionOption]

}

11:33 - Invalidate Offline Key

// Invalidate Offline Key

public class AVContentKeySession {

	func invalidatePersistableContentKey(_ persistableContentKeyData: Data, 
		options: [AVContentKeySessionServerPlaybackContextOption : Any]? = nil, 
		completionHandler handler: @escaping (Data?, Error?) -> Void)


	func invalidateAllPersistableContentKeys(forApp appIdentifier: Data, 
		options: [AVContentKeySessionServerPlaybackContextOption : Any]? = nil, 
		completionHandler handler: @escaping (Data?, Error?) -> Void)


}

13:54 - Quality Selection

// Quality Selection

public class AVAssetDownloadTask {

	public let AVAssetDownloadTaskMinimumRequiredMediaBitrateKey: String

	//Starting in iOS 14

	public let AVAssetDownloadTaskMinimumRequiredPresentationSizeKey: String

	public let AVAssetDownloadTaskPrefersHDRKey: String

}

14:30 - Multichannel Audio Selection

// Multichannel Audio Selection

public class AVAssetDownloadTask {

	public let AVAssetDownloadTaskPrefersMultichannelKey: String

}

15:51 - AVAssetDownloadStorageManager

// AVAssetDownloadStorageManager 
// Get the singleton 
let storageManager = AVAssetDownloadStorageManager.shared()
 
// Create the policy 
let newPolicy = AVMutableAssetDownloadStorageManagementPolicy() 

newPolicy.expirationDate = myExpiryDate

newPolicy.priority = .important 

// Set the policy
storageManager.setStorageManagementPolicy(newPolicy, forURL: myDownloadStorageURL)