Building Mobile Apps (Expo & React Native)

When to use this skill

• When the user asks for an “iOS app”, “Android app”, or “Mobile version”.
• When using React Native or Expo.
• When accessing device features like Camera, Notifications, or Gyroscope.

Workflow

1. Initialization:
   • npx create-expo-app@latest my-app
   • cd my-app && npx expo start
   • Scan QR code with Expo Go app on phone.
2. Navigation:
   • Use expo-router (file-based routing similar to Next.js).
   • Create files in app/index.tsx, app/profile.tsx.
3. Native Features:
   • Install packages: npx expo install expo-camera (auto-configures native code).
4. Build/Deploy:
   • Use EAS Build: eas build --profile production.
   • Submit: eas submit.

Instructions

Project Structure (Expo Router)

/app
  _layout.tsx  # Global provider/navigation stack
  index.tsx    # Home screen
  settings.tsx # /settings screen
/assets        # Images/Fonts
package.json

Core Components

Use React Native primitives, not HTML/CSS tags.

• <div> -> <View>
• <span> -> <Text>
• <button> -> <Pressable> or <TouchableOpacity>
• <img> -> <Image>
• Styling: Use StyleSheet.create or NativeWind (Tailwind for RN).

Code Sharing (Monorepo)

If building a website + mobile app:

• Keep business logic (hooks, state, API calls) in a shared folder.
• Keep UI code separate (React DOM vs React Native) OR use a universal library like Tamagui or NativeBase.

Resources

• Expo Documentation
• React Native Docs
• Expo Router