How to change app language at runtime

This guide will walk you through the necessary steps for changing app language at runtime.

Tip

The complete source code that goes along with this guide is available in the unoplatform/Uno.Samples GitHub repository - RuntimeCultureSwitching

Prerequisites


Tip

For a step-by-step guide to installing the prerequisites for your preferred IDE and environment, consult the Get Started guide.

Step-by-steps

Note

This guide is an extension of "How to use localization", and will build on top the sample from that guide. Make sure you have completed the previous guide or downloaded the full localization sample, before continuing.

  1. Add two new pages to the Localization.Shared project by: Right-click on Localization.Shared > Add > New Item ... > Visual C# > XAML > Blank Page And, name them Page1 and LanguageSettings

  2. Add some content to the two new pages:

    • Page1.xaml:
      <Page x:Class="UnoLocalization.Page1"
            xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
            xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
            xmlns:toolkit="using:Uno.UI.Toolkit">
      
          <StackPanel toolkit:VisibleBoundsPadding.PaddingMask="Top">
              <TextBlock x:Uid="Page1_Title" Text="Page one" FontSize="30" />
      
              <Button x:Uid="Page1_GoBack" Content="Go back" Click="GoBack" />
          </StackPanel>
      </Page>
      
    • Page1.xaml.cs:
      private void GoBack(object sender, RoutedEventArgs e) => Frame.GoBack();
      
    • LanguageSettings.xaml:
      <Page x:Class="UnoLocalization.LanguageSettings"
            xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
            xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
            xmlns:toolkit="using:Uno.UI.Toolkit">
      
          <StackPanel toolkit:VisibleBoundsPadding.PaddingMask="Top">
              <TextBlock x:Uid="LanguageSettings_Title" Text="Language Settings" FontSize="30" />
      
              <Button Content="English" Click="SetAppLanguage" Tag="en" />
              <Button Content="Français" Click="SetAppLanguage" Tag="fr" />
      
              <Button x:Uid="LanguageSettings_GoBack"
                      Content="Go back"
                      Click="GoBack"
                      Margin="0,12,0,0"/>
          </StackPanel>
      </Page>
      
    • LanguageSettings.xaml.cs:
      private void SetAppLanguage(object sender, RoutedEventArgs e)
      {
          if ((sender as Button)?.Tag is string tag)
          {
              // Change the app language
              Windows.Globalization.ApplicationLanguages.PrimaryLanguageOverride = tag;
      
              // Clear the back-navigation stack, and send the user to MainPage
              // This is done because any loaded pages (MainPage(in back-stack) and LanguageSettings (current active page))
              // will stay in the previous language until reloaded.
              Frame.BackStack.Clear();
              Frame.Navigate(typeof(MainPage));
          }
      }
      
      private void GoBack(object sender, RoutedEventArgs e) => Frame.GoBack();
      
  3. Add two new buttons to MainPage for navigation:

    • MainPage.xaml:
      <StackPanel toolkit:VisibleBoundsPadding.PaddingMask="Top">
          <TextBlock x:Uid="MainPage_IntroText" Text="Hello, world!" Margin="20" FontSize="30" />
          <TextBlock x:Name="CodeBehindText" Text="This text will be replaced" />
      
          <Button x:Uid="MainPage_GotoNextPage" Content="Next Page" Click="GotoNextPage" />
          <Button x:Uid="MainPage_GotoLanguageSettings" Content="Language Settings" Click="GotoLanguageSettings" />
      </StackPanel>
      
    • MainPage.xaml.cs:
      private void GotoNextPage(object sender, RoutedEventArgs e) => Frame.Navigate(typeof(Page1));
      private void GotoLanguageSettings(object sender, RoutedEventArgs e) => Frame.Navigate(typeof(LanguageSettings));
      
  4. Add a new folder fr under the Strings folder by: Right-click on String > Add > New Folder

  5. Add a new resource file Resources.resw under the fr folder by: Right-click on fr > Add > New Item ... > Visual C# > Xaml > Resources File

  6. Add the localization strings for the new elements: Open both Strings\en\Resources.resw and Strings\fr\Resources.resw, and add these:

    Name Value in en\Resources.resw Value in fr\Resources.resw
    MainPage_GotoNextPage.Content Next Page Page suivante
    MainPage_GotoLanguageSettings.Content Language Settings Paramètres de langue
    Page1_Title.Text Page in english Page en français
    Page1_GoBack.Content Go back Retourner
    LanguageSettings_Title.Text Language Settings Paramètres de langue
    LanguageSettings_GoBack.Content Go back Retourner

Get the complete code

See the completed sample on GitHub: RuntimeCultureSwitching

Additional Resources

https://docs.microsoft.com/en-us/windows/uwp/design/globalizing/globalizing-portal



Help! I'm having trouble

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