The Evolution of App Theming

Theming used to mean just changing a Primary color. Today, it encompasses Light/Dark modes, High Contrast modes, and sometimes brand-specific skins for white-label applications. A hardcoded color approach will cripple your ability to scale. You need a centralized system where components consume "semantic" colors rather than raw HEX values.

Design Tokens: The Foundation

Don't use Colors.Red. Use Theme.ErrorRed. Design tokens are the bridge between design and code. They define your palette through variables that change their value based on the active theme. This allows you to update your entire app's look by changing a single JSON file or a theme provider object.

Dark Mode Best Practices

True Dark Mode isn't just swapping white for black. Use deep grays to maintain depth through shadows. Avoid pure #000000 for large backgrounds as it can cause "smearing" on OLED screens and makes text harder to read. Desaturate your primary colors for dark backgrounds to ensure they don't "vibrate" against the dark UI.

Theming in SwiftUI & Jetpack Compose

Modern declarative frameworks make theming easy. In SwiftUI, use Color Asset Catalogs with Light and Dark variations. The OS handles the switch automatically. In Jetpack Compose, use a CompositionLocal for your custom Typography and ColorPalette objects, allowing all nested components to react to theme changes instantly.

Dynamic and User-Generated Themes

Apps like Telegram Allow users to build their own themes. This requires a robust architecture where every UI element is mapped to a variable. For white-label apps, you might fetch theme colors from an API on startup. Ensure you have sensible defaults in case the network fails or the custom colors have poor contrast.

Giving users control over their visual environment increases emotional investment in the app.

Handling Asset Variation

Icons and illustrations often need different versions for dark mode. Use "Template Images" (SF Symbols or Android Vectors) that can be tinted programmatically. For complex illustrations, use dual-asset containers that the system automatically picks based on the userInterfaceStyle.

Testing Accessibility in Themes

A beautiful theme is useless if it's unreadable. Use tools to check color contrast ratios (aim for 4.5:1 for normal text). Support the system's "Increase Contrast" setting. Ensure that your interactive elements remain distinct and obvious across all theme variations.