The signature of WidgetsApp.localeListResolutionCallback.
A LocaleListResolutionCallback is responsible for computing the locale of the app's Localizations object when the app starts and when user changes the list of locales for the device.
locales list is the device's preferred locales when the app started, or the
device's preferred locales the user selected after the app was started. This list
is in order of preference. If this list is null or empty, then Flutter has not yet
received the locale information from the platform. The
is just the value of WidgetsApp.supportedLocales.
- LocaleResolutionCallback, which takes only one default locale (instead of a list) and is attempted only after this callback fails or is null. LocaleListResolutionCallback is recommended over LocaleResolutionCallback.
typedef LocaleListResolutionCallback = Locale? Function(List<Locale>? locales, Iterable<Locale> supportedLocales);