Implementing dark mode in Flutter apps

Implementing dark mode in Flutter apps is a great way to enhance user experience by providing a visually comfortable environment, especially in low-light conditions. Here’s a step-by-step guide to help you add dark mode functionality to your Flutter application:

Step 1: Define Your Colors

Start by defining the color palette for both light and dark themes. You can specify these colors in your main.dart file or a separate class for themes.

// Define the color palette
final Color lightPrimary = Colors.white;
final Color darkPrimary = Colors.black;

Step 2: Create ThemeData Instances

Create two instances of ThemeData – one for the light theme and another for the dark theme. Use the colors you defined earlier.

// Light theme
final ThemeData lightTheme = ThemeData(
  primaryColor: lightPrimary,
  // other light theme settings
);

// Dark theme
final ThemeData darkTheme = ThemeData(
  primaryColor: darkPrimary,
  // other dark theme settings
);

Step 3: Apply Themes

In your MaterialApp, apply the themes using the theme and darkTheme properties. To allow the app to automatically switch themes based on the system settings, set the themeMode to ThemeMode.system.

MaterialApp(
  title: 'Flutter Dark Mode Demo',
  theme: lightTheme,
  darkTheme: darkTheme,
  themeMode: ThemeMode.system, // Use ThemeMode.light or ThemeMode.dark to force a particular theme
  home: MyHomePage(),
);

Step 4: Add a Toggle Button

For manual theme switching, create a toggle button that changes the theme when pressed. You can use a Switch widget and manage the state using a ValueNotifier or any state management solution you prefer.

// Example using ValueNotifier
ValueNotifier<ThemeMode> themeNotifier = ValueNotifier(ThemeMode.light);

// In your widget
Switch(
  value: themeNotifier.value == ThemeMode.dark,
  onChanged: (bool isOn) {
    themeNotifier.value = isOn ? ThemeMode.dark : ThemeMode.light;
  },
);

Step 5: Test Your Application

Run your application and test the theme switching functionality. Ensure that all widgets adapt to the theme changes properly.

Additional Tips

Consider using third-party packages like theme_provider, day_night_switcher, or get for more advanced theme management ¹.
Remember to test your app on different devices and OS versions to ensure consistent behavior.

By following these steps, you can successfully implement a dark mode in your Flutter app, providing users with a seamless experience regardless of their preferred theme.