To use the Dark Theme:

1. Add Nuget packages

• Xamarin.Forms.Theme.Base
• Xamarin.Forms.Theme.Dark

2. Add to the Resource Dictionary

In the App.xaml file add a new custom xmlns for the theme, and then ensure the theme's resources are merged with the application's resource dictionary. An example XAML file is shown below:

<?xml version="1.0" encoding="utf-8"?>
<Application xmlns="http://xamarin.com/schemas/2014/forms" xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml" x:Class="EvolveApp.App"
             xmlns:dark="clr-namespace:Xamarin.Forms.Themes;assembly=Xamarin.Forms.Theme.Dark">
    <Application.Resources>
        <ResourceDictionary MergedWith="dark:DarkThemeResources" />
    </Application.Resources>
</Application>

3. Load theme classes

Follow this troubleshooting step and add the required code in the iOS and Android application projects.

4. Use StyleClass

Here is an example of buttons and labels in the dark theme, along with the markup that produces them.

<StackLayout Padding="20">
    <Button Text="Button Default" />
    <Button Text="Button Class Default" StyleClass="Default" />
    <Button Text="Button Class Primary" StyleClass="Primary" />
    <Button Text="Button Class Success" StyleClass="Success" />
    <Button Text="Button Class Info" StyleClass="Info" />
    <Button Text="Button Class Warning" StyleClass="Warning" />
    <Button Text="Button Class Danger" StyleClass="Danger" />
    <Button Text="Button Class Link" StyleClass="Link" />

    <Button Text="Button Class Default Small" StyleClass="Small" />
    <Button Text="Button Class Default Large" StyleClass="Large" />
</StackLayout>

The complete list of built-in classes shows what styles are available for some common controls.