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 a Babel plugin that processes StyleSheets at build time (since 3.6.0, Metro apps can use the experimental zero-config Metro integration instead). It replaces React Native's StyleSheet with a reactive, theme-aware, responsive system.

Prerequisites

• React Native 0.81+ with New Architecture mandatory (enabled by default since RN 0.76, the only architecture since RN 0.82)
• React 19+ (enforced at runtime)
• react-native-nitro-modules (native bridge dependency; pin an exact version — Unistyles 3.4.0+ needs >= 0.37.1)
• iOS 15.1+, Android 7+
• react-native-edge-to-edge is not needed (optional since v3.1.0, now deprecated) — set edgeToEdgeEnabled=true in android/gradle.properties instead (Expo SDK 54+ enables it automatically)
• Expo SDK 54+ (if using Expo; not compatible with Expo Go — requires dev client or prebuild)
• Xcode 16.4+ (iOS, required by Nitro Modules)

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,            // web: themes as CSS variables (default: true)
    // nativeBreakpointsMode: 'pixels' | 'points'  // default 'pixels' = compare against rt.screen (pt/dp)
  }
})

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 (always pass an object, `{}` for defaults)
styles.useVariants({ size: 'large', color: 'primary' })
return <View style={styles.button} />

withUnistyles — map theme/runtime to non-style props, or wrap views Unistyles can't bind to

React Native / Reanimated views that only take style need no wrapping. Use withUnistyles for props like color/trackColor, for contentContainerStyle, or for third-party views that don't expose a native ref.

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" />
// Per-instance mapping: <UniButton uniProps={theme => ({ color: isOn ? theme.colors.on : theme.colors.off })} />

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 — import it directly from react-native-unistyles. Outside root, the Babel plugin only recognizes StyleSheet.create via that import (or autoProcessImports), so a re-export silently breaks detection. (The Metro integration also detects re-exports from your own modules, but direct imports work everywhere.)

3. A build-time integration is REQUIRED — one of:

   • Babel plugin (default): ['react-native-unistyles/plugin', { root: 'src' }] in babel.config.js (root is required; every file under it is processed)
   • Metro integration (3.6.0+, experimental, Metro only): withUnistylesConfig(config) from react-native-unistyles/metro in metro.config.js, no options, and remove the Babel plugin (having both throws). Bare RN apps that list babel-plugin-react-compiler in babel.config.js plugins must keep the Babel plugin — those plugins run before Metro's, so React Compiler would see useVariants first
   • Re.Pack: RepackUnistylePlugin from react-native-unistyles/repack-plugin

   Without one of them, 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). Always pass an object: useVariants(undefined) throws on native, use {} to select default variants.

6. Prefer StyleSheet.create(theme => ...) over useUnistyles() — theme functions cause zero re-renders; useUnistyles() re-renders whenever a theme/rt value you read changes (never read rt.insets.ime there — it re-renders every keyboard frame).

7. StyleSheet.configure() must be called before any StyleSheet.create() — typically in your app entry point, before any component renders.

8. Dynamic function arguments must be serializable — Unistyles stores them in C++ and re-runs the function on theme/runtime changes. Functions are dropped; Date/Map/Set/class instances become plain objects. Pass primitives / plain objects (e.g. date.getTime()).

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                        [re-renders when read values change]
└─ NO  → Use StyleSheet.create with theme function

Third-party component integration

Passing a Unistyles style to `contentContainerStyle` (ScrollView/FlatList)?
├─ YES → withUnistyles(ScrollView) — auto-maps style + contentContainerStyle
└─ NO  → react-native / react-native-reanimated view with a `style` prop?
         ├─ YES → Pass Unistyles styles directly (Babel swaps in ref-borrowing factories)
         └─ NO  → Third-party view built on RN components (in node_modules)?
                  ├─ YES → Metro integration: works as-is (node_modules are covered)
                  │        Babel plugin: add its path to autoProcessPaths (e.g. 'some-lib/src/components')
                  └─ Still not updating / needs theme-derived props (color, size, ...)?
                     ├─ YES → withUnistyles(Component, (theme, rt) => ({ prop: theme.value }))
                     └─ Last resort → useUnistyles() (re-renders the component)

Your own files outside `root` (monorepo package) not updating?
→ autoProcessImports: ['@my-org/styles']  (force-processes any file importing it; not needed with the Metro integration)

Reference Files

• Setup, installation, Babel plugin, Metro integration, Re.Pack, 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/Imports, React Compiler, Reanimated, edge-to-edge, frozen screens, FlatList: read references/third-party-integration.md
• Troubleshooting from 150+ GitHub issues with solutions: read references/common-issues.md