The IETF BCP 47 language tag associated with the option
- iOS 7.0+
- macOS 10.9+
- Mac Catalyst 13.0+Beta
- tvOS 9.0+
- watchOS 2.0+
This property may be
nil indicating that the underlying media presented when the option is selected carries no language information. This can occur with media formats for which language information is optional, such as HTTP Live Streaming playlists, or that do not accommodate language information in machine-readable form.
Clients that are filtering media selection options by language should be prepared to handle cases in which this value is
nil. Further, they should be prepared to handle cases in which an
extended is present but indicates that the language is “undetermined” (a language value of @"und", as defined in ISO 639-2).