CODEWITHSUNDEEP
xamarinxamarin.forms
Rob L
Rob L

Reputation: 2372

Xamarin persist theme

Currently I am only testing on an Android emulator. I have installed the Theme Nuget packages.

In my App constructor I have:

        // Load the desired theme (default to Light)
        if (Current.Properties.TryGetValue("Theme", out object theme))
            Resources = theme as ResourceDictionary;
        else
            Resources = new LightThemeResources();

I then have a method in the App class:

    public async Task SwitchTheme()
    {
        // Switch the current theme from List to Dark to Light
        if (Resources?.GetType() == typeof(DarkThemeResources))
            Resources = new LightThemeResources();
        else
            Resources = new DarkThemeResources();

        // Persist the Theme
        Current.Properties.Add("Theme", Resources);
        await Current.SavePropertiesAsync();
    }

When I call the method the theme switches from light-dark-light etc. But when I restart the App, it always defaults to Light. As if the "await Current.SavePropertiesAsync();" did not work.

Can anyone suggest what the problem may be?

Upvotes: 0

Views: 39

Answers (1)

Jason
Jason

Reputation: 89117

Xamarin Forms Properties is intended for use with C# value types and objects that can be easily serialized - not complex objects like Resources.

From the docs

Values saved in the properties dictionary must be primitive types, such as integers or strings. Attempting to save reference types, or collections in particular, can fail silently.

All you really need to do is store a string value - either 'light' or 'dark' and then load the appropriate theme based on that. You don't actually need to store the theme itself.

Upvotes: 2

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