Xamarin forms turns dark and appshell doesn't work anymore when switching language - xamarin

Question

I implemented language changing trough AppResources.resx files, I have 2 of these: AppResources.resx and AppResources.fr.resx. Switching the language with the following code:
private void Language_switch(object sender, EventArgs e)
{
var lang_switch = Lang.Text;
if (lang_switch == "FR")
{
CultureInfo language = new CultureInfo("fr");
Thread.CurrentThread.CurrentUICulture = language;
AppResources.Culture = language;
}
else
{
CultureInfo language = new CultureInfo("");
Thread.CurrentThread.CurrentUICulture = language;
AppResources.Culture = language;
}
Application.Current.MainPage = new NavigationPage(new PointsPage());
}
The language switches fine but whenever I do, the app turns dark and the AppShell seems to break, it only shows the top bar with toolbar items i made (in what seems to be the standard xamarin color) and showing what seems to be it trying to show the navigation at the bottom, but this only looks like a bar but doesn't seem to have navigation on it and doesn't have any of the labels for navigation.
The content on the page also seems to overlap with this bar going over it if I scroll down. If I press the switch button again it does still switch languages but stay in this dark mode. I don't have any of the dark color set in my app and don't have a dark mode implemented.
It also seems to be doing this on every single page I do it on. How can i stop this from happening so it uses the layout i have made for my app and doesn't turn dark?
Edit: I found out that problem isn't in the language switch. When I go to another page just using
Application.Current.MainPage = new NavigationPage(new PointsPage());
and removing the the language switch code it still does the weird thing where it changes colors. From what it looks like to me is that the page gets put on top without the AppShell moving to be on top of that. Is there a way to reload the AppShell?
Edit2: I managed to fix it. As I suspected the AppShell wasn't reloading and wasn't being put on top of the reloaded page. I added
Application.Current.MainPage = new AppShell();
underneath the page reload and now everything is working

Answer 1

When you use the .resx file to make the localization, create the resx file with the matched file name, when you change the system language, reopen the app would show the matched resource your set in .resx.
For more details about it, you could refer to the MS docs. https://learn.microsoft.com/en-us/xamarin/xamarin-forms/app-fundamentals/localization/text?pivots=windows
Code sample: https://github.com/xamarin/xamarin-forms-samples/tree/main/UsingResxLocalization
If you want to change it at runtime, you could use ResourceManager. It provides convenient access to culture-specific resources at runtime.
I make a simple example for your reference.
MainPage: String1, Settings are the key in .resx file.
<StackLayout>
<Label Text="{Binding Resources[String1]}"
VerticalOptions="Center"
HorizontalOptions="Center" />
<Button Text="{Binding Resources[Settings]}"
HorizontalOptions="Center"
Clicked="Button_Clicked" />
</StackLayout>
Code behind:
public MainPage()
{
InitializeComponent();
this.BindingContext = new MainPageViewModel();
}
private void Button_Clicked(object sender, EventArgs e)
{
Navigation.PushAsync(new SettingsPage());
}
SettingsPage:
<StackLayout>
<Label Text="{Binding Resources[PickLng]}" />
<Picker ItemsSource="{Binding Languages}" SelectedItem="{Binding SelectedLanguage, Mode=TwoWay}" />
</StackLayout>
Code behind:
public SettingsPage()
{
InitializeComponent();
BindingContext = new SettingsViewModel();
}
ViewModel:
public class CultureChangedMessage
{
public CultureInfo NewCultureInfo { get; private set; }
public CultureChangedMessage(string lngName)
: this(new CultureInfo(lngName))
{ }
public CultureChangedMessage(CultureInfo newCultureInfo)
{
NewCultureInfo = newCultureInfo;
}
}
public class LocalizedResources : INotifyPropertyChanged
{
const string DEFAULT_LANGUAGE = "en";
readonly ResourceManager ResourceManager;
CultureInfo CurrentCultureInfo;
public string this[string key]
{
get
{
return ResourceManager.GetString(key, CurrentCultureInfo);
}
}
public LocalizedResources(Type resource, string language = null)
: this(resource, new CultureInfo(language ?? DEFAULT_LANGUAGE))
{ }
public LocalizedResources(Type resource, CultureInfo cultureInfo)
{
CurrentCultureInfo = cultureInfo;
ResourceManager = new ResourceManager(resource);
MessagingCenter.Subscribe<object, CultureChangedMessage>(this,
string.Empty, OnCultureChanged);
}
private void OnCultureChanged(object s, CultureChangedMessage ccm)
{
CurrentCultureInfo = ccm.NewCultureInfo;
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs("Item"));
}
public event PropertyChangedEventHandler PropertyChanged;
}
public class ViewModelBase : INotifyPropertyChanged
{
public LocalizedResources Resources
{
get;
private set;
}
public ViewModelBase()
{
Resources = new LocalizedResources(typeof(AppResources), App.CurrentLanguage);
}
public void OnPropertyChanged([CallerMemberName] string property = null)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(property));
}
public event PropertyChangedEventHandler PropertyChanged;
}
public class MainPageViewModel : ViewModelBase
{ }
public class SettingsViewModel : ViewModelBase
{
public List<string> Languages { get; set; } = new List<string>()
{
"EN",
"FR"
};
private string _SelectedLanguage;
public string SelectedLanguage
{
get { return _SelectedLanguage; }
set
{
_SelectedLanguage = value;
SetLanguage();
}
}
public SettingsViewModel()
{
_SelectedLanguage = App.CurrentLanguage;
}
private void SetLanguage()
{
App.CurrentLanguage = SelectedLanguage;
MessagingCenter.Send<object, CultureChangedMessage>(this,
string.Empty, new CultureChangedMessage(SelectedLanguage));
}
}