Support the system's per-app language setting

How to do it

Android 13 added a system setting where people choose a language for each app. Declare the languages with generateLocaleConfig in the Android Gradle plugin, or a locale_config.xml named in the manifest. Set the language from inside the app with AppCompatDelegate.setApplicationLocales. On iOS, the setting appears for apps with several localizations when the person has more than one preferred language. Add UIPrefersShowingLanguageSettings to show it always. Apple advises opening Settings instead of building your own switch. Save the choice on the account too, as Store language and time zone as two separate settings says, so email follows it.

Examples

Kotlin example

// build.gradle.kts: android { androidResources { generateLocaleConfig = true } }
// res/resources.properties: unqualifiedResLocale=en-US
AppCompatDelegate.setApplicationLocales(LocaleListCompat.forLanguageTags("sv-SE"))

Plain text example

// Info.plist: UIPrefersShowingLanguageSettings = YES
if let settings = URL(string: UIApplication.openSettingsURLString) {
    UIApplication.shared.open(settings)
}

How to check

On a test device with Android 13 or later, the app's system settings page lists every shipped language. Choosing one restarts the app in it. On iOS, the app's Settings page shows a Language row that lists every shipped language.

Sources

• Android Developers (Per-app language preferences)
• Apple WWDC24 (Build multilingual-ready apps)
• Apple WWDC19 (Creating great localized experiences with Xcode 11)

Related rules

• LOC-22 Store language and time zone as two separate settings in Localization
• LOC-38 Translate the store listing for every language the app ships in Localization