Check language in iOS app

Swift 5

Locale.current.regionCode // Optional("US")
Locale.current.languageCode // Optional("en")
Locale.current.identifier // en_US

With extension

extension Locale {
  var isKorean: Bool {
    return languageCode == "ko"
  }
}

Locale.current.isKorean => false

Swift 3 You can take the language code like this

let preferredLanguage = NSLocale.preferredLanguages[0]

And then you need to compare it with code string

if preferredLanguage == "en" {
    print("this is English")
} else if preferredLanguage == "uk" {
    print("this is Ukrainian")
}

You can find codes here

An example to check if French ...

/// Is Device use french language 
/// Consider, "fr-CA", "fr-FR", "fr-CH" et cetera
///
/// - Returns: Bool
static func isFrench() -> Bool {
    return NSLocale.preferredLanguages[0].range(of:"fr") != nil
}