Starting the download

When the application starts a registered download, it is notified that the download has switched to the .downloading state. In the .downloading state, the downloader fetches media segments from the CDN sequentially from the first to the last. When all files of the provided assets have been successfully downloaded, the download state changes to .downloaded. An OTVPersistenceAsset in a .downloaded state would have a valid offlineURL String property.

Options can be passed into the downloader when calling startDownload(). The key-value pairs below may be useful:

• OTVLicenseOptionOffline: Bool (set to true to persistent the licence).

• AVAssetDownloadTaskMinimumRequiredMediaBitrateKey: NSNumber (set the minimum media bitrate).
  If this value is set, the bitrate equal to, or the minimum one greater than, this value is selected to download. The highest bitrate is selected by default if it is not set or no proper value is found. For more information, see the Apple AVAssetDownloadTaskMinimumRequiredMediaBitrateKey documentation.

• AVAssetDownloadTaskMinimumRequiredPresentationSizeKey: NSValue of CGSize (set the minimum resolution, only available on iOS 14 and above).
  If this value is set, the media presentation size equal to, or the minimum one greater than, this value will be selected to download. The highest media presentation size will be selected by default if it is not set or no proper value is found. For more information, see the Apple AVAssetDownloadTaskMinimumRequiredPresentationSizeKey documentation.

The AVAssetDownloadTaskMinimumRequiredMediaBitrateKey and 
AVAssetDownloadTaskMinimumRequiredPresentationSizeKey cannot guarantee the actual download bitrate or resolution will equal the expected value; see Selecting the download stream.

Example code

Setting options to persist the licence

var yourOptions = [OTVLicenseOptionOffline : true]

Setting options to select the minimum bitrate for download

yourOptions[AVAssetDownloadTaskMinimumRequiredMediaBitrateKey] = 600000

Setting options to select the minimum resolution for download

yourOptions[AVAssetDownloadTaskMinimumRequiredPresentationSizeKey] = NSValue(cgSize: CGSize(width: 1280, height:  720))

Starting the download with yourOptions

func startDownloadAsset(url: URL, assetName: String) -> (Bool, String, OTVPersistenceAsset?) {
  // If download a stream encrypted using FPS, create an instance of OTVLicenseDelegate and set licenseDelegate when starting the download.
  // E.g. create an instance of OTVSSPLicenseDelegate with FairPlay certificate url and license url with SSP server, and set the stream token for download asset
  // If download a clear stream, set licenseDelegate with nil.
  let delegate = OTVSSPLicenseDelegate(certificateURL: certificateUrl, licenseURL: licenseUrl)
  delegate.setStream(token: streamToken, with url: url)
  
  if let asset = OTVPersistenceManager.sharedManager.startDownload(urlAsset: OTVAVURLAsset(url: url), title: assetName, licenseDelegate: delegate, artwork: nil, options: yourOptions) {
    return (true, "", asset)
  }
  return (false, "download did not start", nil)
}

Pausing a download

OTVPersistenceManager.sharedManager.pauseDownload(asset: OTVPersistenceAsset)

Resuming a download

OTVPersistenceManager.sharedManager.resumeDownload(asset: OTVPersistenceAsset)

Next step: You can play the download.