React Native Patterns

React Native Patterns

Build production-quality mobile apps with React Native and Expo.

Project Setup

Expo (recommended for most projects):

npx create-expo-app@latest my-app
cd my-app
npx expo start

Bare React Native (when you need full native control):

npx @react-native-community/cli init MyApp

Use Expo unless you need a custom native module that Expo doesn't support.

Navigation

Use expo-router (file-based routing) or @react-navigation/native:

app/
├── _layout.tsx        # Root layout (tabs, stack, drawer)
├── index.tsx          # Home screen
├── (tabs)/
│   ├── _layout.tsx    # Tab navigator
│   ├── home.tsx
│   ├── profile.tsx
│   └── settings.tsx
└── [id].tsx           # Dynamic route

Platform-Specific Code

import { Platform } from 'react-native';

const styles = StyleSheet.create({
  shadow: Platform.select({
    ios: { shadowColor: '#000', shadowOffset: { width: 0, height: 2 }, shadowOpacity: 0.1 },
    android: { elevation: 4 },
  }),
});

For larger differences, use platform-specific files:

• Component.ios.tsx
• Component.android.tsx

Styling

Use StyleSheet.create for performance (styles are sent to native once):

const styles = StyleSheet.create({
  container: { flex: 1, padding: 16 },
  title: { fontSize: 24, fontWeight: '700' },
});

For a Tailwind-like experience, use nativewind:

<View className="flex-1 p-4">
  <Text className="text-2xl font-bold">Hello</Text>
</View>

Performance

FlatList over ScrollView for long lists:

<FlatList
  data={items}
  keyExtractor={(item) => item.id}
  renderItem={({ item }) => <ItemRow item={item} />}
  initialNumToRender={10}
  maxToRenderPerBatch={5}
  windowSize={5}
/>

Memoize expensive components:

const ItemRow = React.memo(({ item }: { item: Item }) => (
  <View><Text>{item.name}</Text></View>
));

Avoid:

• Inline styles (creates new objects every render)
• Anonymous functions in renderItem
• Large images without caching (expo-image handles this)

Common Libraries

Tips

• Test on both iOS and Android from the start, not at the end
• Use expo-dev-client for custom native modules with Expo
• Handle safe areas with react-native-safe-area-context
• Always handle keyboard avoidance for forms (KeyboardAvoidingView)
• Use expo-updates for OTA updates in production