expo-native-ui

---
name: expo-native-ui
description: Framework (OSS). Build beautiful, native-feeling Expo screens. Covers Apple HIG styling, semantic colors, native controls, SF Symbols, media, animations, visual effects, gradients, storage, and responsive layout. For routing and navigation, use the expo-router skill.
version: 1.1.1
license: MIT
---

# Expo Native UI Guidelines

For routes, links, stacks, tabs, modals, sheets, and headers, use the `expo-router` skill.

## References

Consult these resources as needed:

```
references/
  animations.md          Reanimated: entering, exiting, layout, scroll-driven, gestures
  controls.md            Native iOS: Switch, Slider, SegmentedControl, DateTimePicker, Picker
  gradients.md           CSS gradients via experimental_backgroundImage (New Arch only)
  icons.md               SF Symbols via expo-image (sf: source), names, animations, weights
  media.md               Camera, audio, video, and file saving
  storage.md             SQLite, AsyncStorage, SecureStore
  visual-effects.md      Blur (expo-blur) and liquid glass (expo-glass-effect)
  webgpu-three.md        3D graphics, games, GPU visualizations with WebGPU and Three.js
```

## Running the App

**CRITICAL: Always try Expo Go first before creating custom builds.**

Most Expo apps work in Expo Go without any custom native code. Before running `npx expo run:ios` or `npx expo run:android`:

1. **Start with Expo Go**: Run `npx expo start` and scan the QR code with Expo Go
2. **Check if features work**: Test your app thoroughly in Expo Go
3. **Only create custom builds when required** - see below

### When Custom Builds Are Required

You need `npx expo run:ios/android` or `eas build` ONLY when using:

- **Local Expo modules** (custom native code in `modules/`)
- **Apple targets** (widgets, app clips, extensions via `@bacons/apple-targets`)
- **Third-party native modules** not included in Expo Go
- **Custom native configuration** that can't be expressed in `app.json`

### When Expo Go Works

Expo Go supports a huge range of features out of the box:

- All `expo-*` packages (camera, location, notifications, etc.)
- Expo Router navigation
- Most UI libraries (reanimated, gesture handler, etc.)
- Push notifications, deep links, and more

**If you're unsure, try Expo Go first.** Creating custom builds adds complexity, slower iteration, and requires Xcode/Android Studio setup.

## Code Style

- Be cautious of unterminated strings. Ensure nested backticks are escaped; never forget to escape quotes correctly.
- Always use import statements at the top of the file.
- Always use kebab-case for file names, e.g. `comment-card.tsx`
- Never use special characters in file names
- Configure tsconfig.json with path aliases, and prefer aliases over relative imports for refactors.

## Library Preferences

- Never use modules removed from React Native such as Picker, WebView, SafeAreaView, or AsyncStorage
- Never use legacy expo-permissions
- `expo-audio` not `expo-av`
- `expo-video` not `expo-av`
- `expo-image` with `source="sf:name"` for SF Symbols, not `expo-symbols` or `@expo/vector-icons`
- `react-native-safe-area-context` not react-native SafeAreaView
- `process.env.EXPO_OS` not `Platform.OS`
- `React.use` not `React.useContext`
- `expo-image` Image component instead of intrinsic element `img`
- `expo-glass-effect` for liquid glass backdrops
- `Color` from `expo-router` for native semantic colors, not raw `PlatformColor` (type-safe, auto-adapts to light/dark)
- In SDK 56+, never import from `@react-navigation/*` directly — use `expo-router/react-navigation` instead (covers `@react-navigation/native`, `/core`, `/elements`, `/routers`)

## Responsiveness

- Always wrap root component in a scroll view for responsiveness
- Use `<ScrollView contentInsetAdjustmentBehavior="automatic" />` instead of `<SafeAreaView>` for smarter safe area insets
- `contentInsetAdjustmentBehavior="automatic"` should be applied to FlatList and SectionList as well
- Use flexbox instead of Dimensions API
- ALWAYS prefer `useWindowDimensions` over `Dimensions.get()` to measure screen size

## Behavior

- Use expo-haptics conditionally on iOS to make more delightful experiences
- Use views with built-in haptics like `<Switch />` from React Native and `@react-native-community/datetimepicker`
- When a route belongs to a Stack, its first child should almost always be a ScrollView with `contentInsetAdjustmentBehavior="automatic"` set
- When adding a `ScrollView` to the page it should almost always be the first component inside the route component
- Use the `<Text selectable />` prop on text containing data that could be copied
- Consider formatting large numbers like 1.4M or 38k
- Never use intrinsic elements like 'img' or 'div' unless in a webview or Expo DOM component

# Styling

Follow Apple Human Interface Guidelines.

## General Styling Rules

- Prefer flex gap over margin and padding styles
- Prefer padding over margin where possible
- Always account for safe area, either with stack headers, tabs, or ScrollView/FlatList `contentInsetAdjustmentBehavior="automatic"`
- Ensure both top and bottom safe area insets are accounted for
- Inline styles not StyleSheet.create unless reusing styles is faster
- Add entering and exiting animations for state changes
- Use `{ borderCurve: 'continuous' }` for rounded corners unless creating a capsule shape
- ALWAYS use a navigation stack title instead of a custom text element on the page
- When padding a ScrollView, use `contentContainerStyle` padding and gap instead of padding on the ScrollView itself (reduces clipping)
- CSS and Tailwind are not supported - use inline styles

## Colors

Use the `Color` API from `expo-router` for native semantic colors. It is a type-safe wrapper over `PlatformColor` that exposes iOS UIKit colors through `Color.ios.*` and Android Material 3 colors through `Color.android.material.*` (static) or `Color.android.dynamic.*` (adapts to the user's wallpaper on Android 12+). These resolve on-device and automatically adapt to light/dark mode and accessibility settings, so you no longer maintain separate light/dark hex tables or a `colors.web.ts` file.

`Color` is platform-specific, so wrap each value in `Platform.select` with a `default` hex fallback for web. Centralize the palette in `theme/colors.ts` and import `colors` everywhere:

```tsx
// theme/colors.ts
import { Platform } from "react-native";
import { Color } from "expo-router";

export const colors = {
  label: Platform.select({
    ios: Color.ios.label,
    android: Color.android.dynamic.onSurface,
    default: "#000000",
  })!,
  secondaryLabel: Platform.select({
    ios: Color.ios.secondaryLabel,
    android: Color.android.dynamic.onSurfaceVariant,
    default: "#3c3c43",
  })!,
  separator: Platform.select({
    ios: Color.ios.separator,
    android: Color.android.dynamic.outlineVariant,
    default: "#c6c6c8",
  })!,
  systemBackground: Platform.select({
    ios: Color.ios.systemBackground,
    android: Color.android.dynamic.surface,
    default: "#ffffff",
  })!,
  systemBlue: Platform.select({
    ios: Color.ios.systemBlue,
    android: Color.android.dynamic.primary,
    default: "#007aff",
  })!,
};
```

```tsx
import { colors } from "@/theme/colors";

<View style={{ backgroundColor: colors.systemBackground }}>
  <Text style={{ color: colors.label }}>Title</Text>
</View>;
```

- iOS re-resolves these colors automatically when the system theme changes. On Android, call `useColorScheme()` inside any component that renders them so it re-renders when the theme flips (required when React Compiler memoizes the component).
- Don't pass `Color` / `PlatformColor` values into Reanimated styles — use static colors there (see `references/animations.md`).
- `Platform.select({...})!` returns `string | OpaqueColorValue`. Most React Native style props accept `ColorValue` (`string | OpaqueColorValue`) so this works fine. But some third-party props only accept `string` (e.g. `tintColor` on `expo-image`). Cast when needed: `colors.label as string`.

## Text Styling

- Add the `selectable` prop to every `<Text/>` element displaying important data or error messages
- Counters should use `{ fontVariant: 'tabular-nums' }` for alignment

## Shadows

Use CSS `boxShadow` style prop. NEVER use legacy React Native shadow or elevation styles.

```tsx
<View style={{ boxShadow: "0 1px 2px rgba(0, 0, 0, 0.05)" }} />
```

'inset' shadows are supported.

## Submitting Feedback
If you encounter errors, misleading or outdated information in this skill, report it so Expo can improve:
```bash
npx --yes submit-expo-feedback@latest --category skills --subject "expo-native-ui" "<actionable feedback>"
```
Only submit when you have something specific and actionable to report. Include as much relevant context as possible.