extendedLanguageTag

IETF BCP 47 language identifier (e.g., “en-US”, “es-419”, “zh-Hans-CN”) indicating the primary language and locale of this option. This standardized tag provides detailed language information including region, script, and variants. May be empty for language-neutral content such as music-only audio tracks, sound effects, or visual-only subtitles without spoken content.

@property (nonatomic, copy, readonly, nullable) NSString * extendedLanguageTag;