React Native Unistyles V3

React Native Unistyles v3 Skill

You are assisting with React Native Unistyles v3 styling. v3 is a zero-re-render styling library with a C++ core (Nitro Modules) and Babel plugin that processes StyleSheets at build time. It replaces React Native's StyleSheet with a reactive, theme-aware, responsive system.

Prerequisites

• React Native 0.78+ with New Architecture mandatory (default from RN 0.83+)
• React 19+ (enforced at runtime)
• react-native-nitro-modules (native bridge dependency)
• react-native-edge-to-edge (required for Android edge-to-edge insets)
• Expo SDK 53+ (if using Expo; not compatible with Expo Go — requires dev client or prebuild)
• Xcode 16+ (iOS)

Workflow

1. Read user's code first — understand current setup, imports, and styling approach
2. Identify intent — new setup, add theming, responsive design, fix an issue, etc.
3. Apply v3 patterns — use the correct API from this skill; consult reference files for details
4. Verify correctness — check for critical rule violations (spreading, barrel re-exports, etc.)

Quick Reference

StyleSheet.create — 3 overloads

import { StyleSheet } from 'react-native-unistyles'

// 1. Static object compatible with React Native StyleSheet.create
const styles = StyleSheet.create({
  container: { flex: 1, padding: 16 }
})

// 2. Theme function (reactive to theme changes, zero re-renders)
const styles = StyleSheet.create(theme => ({
  container: { backgroundColor: theme.colors.background }
}))

// 3. Theme + miniRuntime function (reactive to theme AND device state)
const styles = StyleSheet.create((theme, rt) => ({
  container: {
    backgroundColor: theme.colors.background,
    paddingTop: rt.insets.top,
    width: rt.screen.width > 768 ? 500 : rt.screen.width - 32
  }
}))

StyleSheet.configure — one-time setup

StyleSheet.configure({
  themes: { light: lightTheme, dark: darkTheme },
  breakpoints: { xs: 0, sm: 576, md: 768, lg: 992, xl: 1200 },
  settings: {
    initialTheme: 'light',       // or: () => storage.getString('theme') ?? 'light'
    // adaptiveThemes: true,     // auto-switch light/dark based on OS (mutually exclusive with initialTheme)
    // CSSVars: true,            // use CSS custom properties on web
    // nativeBreakpointsMode: 'pixels' | 'points'
  }
})

Variants

const styles = StyleSheet.create(theme => ({
  button: {
    variants: {
      size: {
        small: { padding: 4 },
        medium: { padding: 8 },
        large: { padding: 16 },
      },
      color: {
        primary: { backgroundColor: theme.colors.primary },
        secondary: { backgroundColor: theme.colors.secondary },
      }
    },
    compoundVariants: [
      { size: 'large', color: 'primary', styles: { borderWidth: 2 } }
    ],
  }
}))

// In component — call useVariants BEFORE accessing styles
styles.useVariants({ size: 'large', color: 'primary' })
return <View style={styles.button} />

withUnistyles — wrap third-party components (not React Native or Reanimated components)

import { withUnistyles } from 'react-native-unistyles'
import { Button } from 'some-library'

const UniButton = withUnistyles(Button, (theme, rt) => ({
  color: theme.colors.primary,
  size: rt.screen.width > 400 ? 'large' : 'small'
}))

// Usage: <UniButton title="Press me" />

Critical Rules

1. NEVER spread styles — {...styles.x} breaks C++ proxy binding. ALWAYS use array syntax: [styles.x, styles.y] or [styles.x, { marginTop: 10 }]
2. NEVER re-export StyleSheet from barrel files — the Babel plugin detects StyleSheet.create by import source. Re-exporting breaks detection.
3. Babel plugin is REQUIRED — add ['react-native-unistyles/plugin', { root: 'src' }] to babel.config.js. Without it, styles won't be reactive.
4. Import StyleSheet from react-native-unistyles only — it polyfills all RN StyleSheet APIs (hairlineWidth, compose, flatten, absoluteFill). Replace all import { StyleSheet } from 'react-native'.
5. styles.useVariants() must be called before accessing variant-dependent styles — treat it like a React hook (top of component).
6. Prefer StyleSheet.create(theme => ...) over useUnistyles() — theme functions cause zero re-renders; useUnistyles() re-renders on every theme/runtime change.
7. StyleSheet.configure() must be called before any StyleSheet.create() — typically in your app entry point, before any component renders.

Decision Trees

Choosing a styling approach

Need theme/runtime in styles?
├─ YES → StyleSheet.create((theme, rt) => ...)     [zero re-renders]
└─ NO  → StyleSheet.create({ ... })                [static styles]

Need theme values as non-style props?
├─ YES → withUnistyles(Component, (theme, rt) => ({ propName: theme.value }))
└─ NO  → Pass Unistyles styles via style prop directly

Need theme/runtime in component logic (not just styles)?
├─ YES → useUnistyles() hook                        [causes re-renders]
└─ NO  → Use StyleSheet.create with theme function

Third-party component integration

Does the component accept a `style` prop?
├─ YES → Pass Unistyles styles directly (Babel auto-processes standard RN views)
│        If it's a custom native view → add to autoProcessPaths in Babel config
├─ NO  → Does it accept theme-derived props (color, size, etc.)?
│        ├─ YES → withUnistyles(Component, (theme, rt) => ({ prop: theme.value }))
│        └─ NO  → useUnistyles() as fallback
└─ Component from node_modules not processed?
   → Add its path to autoProcessPaths or autoProcessImports in Babel plugin config

Reference Files

• Setup, installation, Babel plugin, TypeScript, testing, Expo Router: read references/setup-guide.md
• Complete API for every export: read references/api-reference.md
• Code patterns: themes, variants, breakpoints, web, SSR, Reanimated: read references/styling-patterns.md
• withUnistyles, autoProcessPaths, React Compiler, Reanimated, FlatList: read references/third-party-integration.md
• Troubleshooting from 150+ GitHub issues with solutions: read references/common-issues.md