No, it's the latter.

In NSLocale, "region" is a subtype of language, as in a regional dialect, not an independent dimension.

https://developer.apple.com/documentation/foundation/nslocal...

https://developer.apple.com/library/archive/documentation/Ma...

Nope, [[NSLocale currentLocale] countryCode] returns Region country code from settings. The same code is also used for language region, so you can end up with something like zh_US.