React Native Skill

Overview

Mobile development patterns with React Native for iOS and Android applications.

Objective

Guide developers in building cross-platform mobile apps with React Native using proper patterns and performance optimization.

Extended Mandatory Read Protocol

This skill uses the Extended Mandatory Read Protocol for complex React Native patterns (40+ patterns total).

Reading Strategy

1. ALWAYS read: This main SKILL.md (covers 80% of common React Native cases)
2. Read references/ when:
   • Decision Tree indicates "MUST read {reference}"
   • Quick Reference Table marks it "Required Reading: ✅"
   • Critical Pattern says "[CRITICAL] See {reference} for..."
   • Working with advanced features (navigation, animations, native modules)

When to Read References

Available References

All reference files located in skills/react-native/references/:

• README.md: Overview of all React Native references and navigation guide
• navigation-patterns.md: React Navigation Stack/Tab/Drawer, deep linking (required for navigation)
• gestures-animations.md: Gesture Handler, Animated API, Reanimated (required for animations)
• platform-specific.md: Platform.select, iOS/Android differences (required for platform code)
• performance-rn.md: FlatList optimization, memory management (required for optimization)
• native-modules.md: Linking native code, bridges (required for native integration)

Conditional Language

• "MUST read" → Obligatory - Read immediately before proceeding
• "CHECK" or "Consider" → Suggested - Read if you need deeper understanding
• "OPTIONAL" → Ignorable - Read only for learning or edge cases

Example: Navigation Task

1. User: "Set up Stack and Tab navigation"
2. Read: skills/react-native/SKILL.md (this file)
3. Check Decision Tree: "Navigation? → MUST read navigation-patterns.md"
4. Read: skills/react-native/references/navigation-patterns.md (REQUIRED)
5. Execute: Implement Stack and Tab navigators with React Navigation

When to Use

Use this skill when:

• Building cross-platform mobile apps (iOS + Android)
• Using bare React Native (not Expo managed workflow)
• Implementing platform-specific features
• Optimizing mobile performance
• Integrating native modules

Don't use this skill for:

• Expo managed workflow (use expo skill)
• Web-only React apps (use react skill)
• Native iOS/Android development

Critical Patterns

✅ REQUIRED: Use FlatList for Lists

// ✅ CORRECT: Virtualized list
<FlatList
  data={items}
  keyExtractor={(item) => item.id}
  renderItem={({ item }) => <Item data={item} />}
/>

// ❌ WRONG: ScrollView with map (memory issues)
<ScrollView>
  {items.map(item => <Item key={item.id} data={item} />)}
</ScrollView>

✅ REQUIRED: Use Platform-Specific Code

// ✅ CORRECT: Platform.select or Platform.OS
import { Platform } from "react-native";

const styles = StyleSheet.create({
  container: {
    padding: Platform.select({ ios: 10, android: 8 }),
  },
});

// Or separate files: Component.ios.tsx, Component.android.tsx

✅ REQUIRED: Handle Safe Areas

// ✅ CORRECT: SafeAreaView
import { SafeAreaView } from 'react-native-safe-area-context';

<SafeAreaView>
  <App />
</SafeAreaView>

// ❌ WRONG: No safe area handling (notch issues)
<View>
  <App />
</View>

✅ REQUIRED: Optimize Images

// ✅ CORRECT: Specify dimensions, use FastImage for remote images
<Image
  source={{ uri: url }}
  style={{ width: 200, height: 200 }}
  resizeMode="cover"
/>

// ❌ WRONG: No dimensions (layout thrashing)
<Image source={{ uri: url }} />

Conventions

Refer to conventions for:

• Code organization

Refer to a11y for:

• Accessibility labels
• Screen reader support

Refer to react for:

• Component patterns
• Hooks usage

React Native Specific

• Use Platform-specific code when necessary
• Implement proper list virtualization with FlatList
• Handle safe areas properly
• Optimize images and assets
• Use Hermes engine for better performance

Decision Tree

Long list? → Use FlatList with keyExtractor and getItemLayout for optimization. [CRITICAL] See references/performance-rn.md for FlatList optimization.

Platform-specific styling? → Use Platform.select() or Platform.OS === 'ios'. [CRITICAL] See references/platform-specific.md for platform patterns.

Navigation? → Use React Navigation library. [CRITICAL] See references/navigation-patterns.md for Stack/Tab/Drawer setup.

Gestures/Animations? → Use Gesture Handler + Reanimated. [CRITICAL] See references/gestures-animations.md for gesture and animation patterns.

Forms? → Use controlled components, consider react-hook-form for complex forms.

State management? → Context for simple, Redux/Zustand for complex.

Native feature needed? → Check if React Native API exists, otherwise use native module or library. [CRITICAL] See references/native-modules.md for native integration.

Performance issue? → Enable Hermes, use React.memo(), avoid inline functions in renders, profile with Flipper. [CRITICAL] See references/performance-rn.md for optimization strategies.

Testing? → Use Jest + React Native Testing Library, test on real devices.

Example

import { View, Text, FlatList, Platform } from 'react-native';

const MyList = ({ items }) => (
  <FlatList
    data={items}
    keyExtractor={(item) => item.id}
    renderItem={({ item }) => (
      <View style={{ padding: Platform.OS === 'ios' ? 10 : 8 }}>
        <Text>{item.name}</Text>
      </View>
    )}
  />
);

Advanced Architecture Patterns

⚠️ Context Check: Architecture patterns apply to React Native the same way as React. Mobile apps with business logic benefit from architecture patterns.

When to Apply

• AGENTS.md mentions architecture: Project specifies "Clean Architecture", "SOLID", "DDD"
• Enterprise mobile apps: Banking, healthcare, fintech, ERP apps
• Complex business logic: Authentication, payments, offline sync, data transformations
• Large teams: >10 developers requiring consistent structure

When NOT to Apply

• Simple apps (content display, basic forms)
• Prototypes or MVPs
• No mention in AGENTS.md

Architecture Integration

React Native uses same patterns as React:

• SOLID Principles → Service classes, custom hooks, components
• Clean Architecture → domain/, application/, infrastructure/, mobile/ (presentation)
• Result Pattern → Async operations, API calls, local storage
• DIP → Abstract services (API, storage, permissions) with adapters

Mobile-specific architecture:

// domain/entities/User.ts (same as web)
export class User {
  constructor(
    public readonly id: string,
    public readonly email: string
  ) {}
}

// infrastructure/services/SecureStorageService.ts (mobile adapter)
export class SecureStorageService implements IStorageService {
  async save(key: string, value: string): Promise<Result<void>> {
    try {
      await SecureStore.setItemAsync(key, value); // Expo SecureStore
      return Result.ok(undefined);
    } catch (error) {
      return Result.fail('Storage error');
    }
  }
}

// mobile/screens/LoginScreen.tsx (presentation)
const LoginScreen = () => {
  const { execute, result } = useLoginUser(); // Clean Architecture use case

  return (
    <View>
      <TextInput onChangeText={setEmail} />
      <Button onPress={() => execute(email, password)} title="Login" />
      {result && !result.isSuccess && <Text>{result.error}</Text>}
    </View>
  );
};

For Complete Guide

MUST read architecture-patterns/references/frontend-integration.md - React Native uses same patterns as React.

Also see: architecture-patterns/SKILL.md for pattern selection.

Edge Cases

Keyboard handling: Use KeyboardAvoidingView or react-native-keyboard-aware-scroll-view.

Android back button: Handle with BackHandler API, especially for modals.

Permissions: Request runtime permissions on Android 6+, handle denied state gracefully.

Deep linking: Configure URL schemes for both iOS and Android, handle different app states.

Offline support: Use NetInfo to detect connectivity, queue operations when offline.

Bundle size: Use Hermes, enable ProGuard on Android, analyze bundle with Metro.

Debugging: Use Flipper for network/Redux inspection, React DevTools, Chrome debugger.

References

• https://reactnative.dev/docs/getting-started
• https://reactnative.dev/docs/performance