How to save background color on close

Question

I'm doing an android game with Xamarin Forms and in this game you can choose if the theme is dark or light. What I did is creating staticressources (colors) in App.xmal.

<Application.Resources>

    <Color x:Key="PrincipalColor" >#181818</Color>
    <Color x:Key="PrincipalColorInvert" >#ffffff</Color>

</Application.Resources>

But when the user changes the theme (the staticressources color) and quit the game it doesn't save his preferences. I heard about "App.Current.Properties["Id"] =..." but I can't figure it out. If someone know how to do i'll be happy to know. Thank you.

Answer 1

You can use Xamarin.Essentials: Preferences

https://learn.microsoft.com/en-us/xamarin/essentials/preferences?tabs=android

Save a color in Resources , in the example with a Button set a color Green or Red.

In MainPage.xaml at the top

BackgroundColor="{DynamicResource defaultBackgroundColor}"

Then the Buttons

  <Button Clicked="Button_Clicked" Text="Green" />

    <Button Clicked="Button_Clicked_1" Text="Red" />

In MainPage.xaml.cs using Xamarin.Essentials;

 public MainPage()
    {
        InitializeComponent();
        App.Current.Resources["defaultButtonBackgroundColor"] = Preferences.Get("defaultButtonBackgroundColor", "Blue");
    }

    private void Button_Clicked(object sender, EventArgs e)
    {
        Preferences.Set("BackgroundColor", "Green");
        App.Current.Resources["defaultBackgroundColor"] = Preferences.Get("BackgroundColor", "Blue");
    }

    private void Button_Clicked_1(object sender, EventArgs e)
    {
        Preferences.Set("BackgroundColor", "Red");
        App.Current.Resources["defaultBackgroundColor"] = Preferences.Get("BackgroundColor", "Blue");
    }

Also use it for change TextColor of a Button etc, PricipalColor for example.

StaticResource is set and DynamicResource you can change

App.xaml.cs

    <Application.Resources>

    <Color x:Key="PrincipalColor" >#181818</Color>

</Application.Resources>

MainPage.xaml.cs

   public MainPage()
    {
        InitializeComponent();
        App.Current.Resources["defaultButtonBackgroundColor"] = Preferences.Get("defaultButtonBackgroundColor", "Blue");
        App.Current.Resources["PrincipalColor"] = Preferences.Get("PrincipalColor", "#181818");
    }

Change and PrincipalColor to White or any other color with Button.

 private void Button_Clicked(object sender, EventArgs e)
    {
        Preferences.Set("PrincipalColor", "White");
        App.Current.Resources["PrincipalColor"] = Preferences.Get("PrincipalColor", "#181818");
    }

MainPage.xaml in the first Button is Static and the 2e Dynamic changes TextColor

<Button Clicked="Button_Clicked" Text="Green" TextColor="{StaticResource PrincipalColor}" />

    <Button Clicked="Button_Clicked_1" Text="Red" TextColor="{DynamicResource PrincipalColor}" />