uses FMX.Platform{$IFDEF MSWINDOWS}, WinAPi.Windows{$ENDIF};

function GetLang: string;

var

  LocaleService: IFMXLocaleService;

begin

  Result := '';

  if TPlatformServices.Current.SupportsPlatformService(IFMXLocaleService, IInterface(LocaleService)) then

  begin

    Result := LocaleService.GetCurrentLangID;

  end;

end;