The default language and region for the bundle, as a language ID.
- iOS 2.0+
- macOS 10.0+
- tvOS 9.0+
- watchOS 2.0+
- Core Foundation
- Localization native development region
The system uses this key as the language if it can't locate a resource for the user’s preferred language. The value should be a language ID that identifies a language, dialect, or script.
For a language used in many regions, use a code that represents a language designator. To specify English, use the en language designator. Use the two-letter ISO 639-1 standard (preferred) or the three-letter ISO 639-2 standard. If an ISO 639-1 code isn't available for a particular language, use the ISO 639-2 code instead. There's no ISO 639-1 code for the Hawaiian language, so use the ISO 639-2 code.
To distinguish between different languages and regional dialects, use a language designator with a region designator and a script designator separated by hyphens. To specify the English language as it's used in the United Kingdom, use en-GB, where GB is the region designator. To represent Mandarin Chinese, spoken in Taiwan, and written in Traditional Chinese script, use zh-Hant-TW.
To specify a script, combine a language designator with a script designator separated by a hyphen, as in az-Arab for Azerbaijani in the Arabic script.