xamarin.forms: Changing language at runtim doesnt affect UI Hi - xamarin.forms

Question

I am having an app where the user picks his or her language:
I have two resources files, both of which work because I can see the text showing up in Xaml.
A short overview:
Eng Resource:
<data name="Next" xml:space="preserve">
<value>next</value>
</data>
<data name="German" xml:space="preserve">
<value>German</value>
</data>
<data name="Arabic" xml:space="preserve">
<value>Arabic</value>
</data>
The Labels:
<Label Text="{x:Static resources:AppResources.German}"
VerticalOptions="Center"
Grid.Row="0"/>
<Label Text="{x:Static resources:AppResources.Arabic}"
VerticalOptions="Center"
Grid.Row="1"/>
<Label Text="{x:Static resources:AppResources.English}"
VerticalOptions="Center"
Grid.Row="2"/>
I know that they work, becaause when I change from one emulator to another (one in germany, one in england) the language changes automatically.
But I want the user to be able to change the language upon button click.
I tried:
case "english":
CultureInfo culture = new CultureInfo("en-US");
CultureInfo.DefaultThreadCurrentCulture = culture;
mainPage.FlowDirection = FlowDirection.LeftToRight;
break;
But the phone simply ignores the language change.
Any ideas why?

Answer 1

You can create a LocalizationResourceManager class that handles language changes and also will have a property with the translation. When the language changes it will invalidate that string so it will force the property to change.
public class LocalizationResourceManager : INotifyPropertyChanged
{
public static LocalizationResourceManager Instance { get; } = new LocalizationResourceManager();
public string this[string text]
{
get
{
return AppResources.ResourceManager.GetString(text, AppResources.Culture);
}
}
public void SetCulture(CultureInfo language)
{
Thread.CurrentThread.CurrentUICulture = language;
AppResources.Culture = language;
Invalidate();
}
public event PropertyChangedEventHandler PropertyChanged;
public void Invalidate()
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(null));
}
}
Instead of binding our strings directly to the AppResources class, a Translate Extension that returns a BindingProperty is used and binds to our new LocalizationResourceManager.
[ContentProperty("Text")]
public class TranslateExtension : IMarkupExtension<BindingBase>
{
public string Text { get; set; }
public string StringFormat { get; set; }
object IMarkupExtension.ProvideValue(IServiceProvider serviceProvider)
{
return ProvideValue(serviceProvider);
}
public BindingBase ProvideValue(IServiceProvider serviceProvider)
{
var binding = new Binding
{
Mode = BindingMode.OneWay,
Path = $"[{Text}]",
Source = LocalizationResourceManager.Instance,
StringFormat= StringFormat
};
return binding;
}
}
Usage:
<?xml version="1.0" encoding="UTF-8"?>
<ContentPage xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
x:Class="MultilingualXFSample.Views.ChangeLanguagePage"
xmlns:helpers="clr-namespace:MultilingualXFSample.Helpers">
<Label Text="{helpers:Translate SelectLanguage}" />
</ContentPage>
For more, you can check: Mastering Multilingual in Xamarin.Forms
And there is a sample here: https://github.com/CrossGeeks/MasteringMultilingualSample .