React Native Mobile Development
Guide for building mobile apps with React Native and Expo.
When to Use
- •Setting up React Native/Expo projects
- •Running dev servers or builds
- •Creating mobile components
- •Handling platform-specific code (iOS/Android)
- •Configuring app.json or native modules
- •Troubleshooting mobile-specific issues
Core Commands
bash
# Development npm start # Start Metro bundler npm run ios # Run on iOS Simulator npm run android # Run on Android Emulator # Expo specific npx expo start # Start with Expo CLI npx expo install PKG # Install compatible packages npx expo prebuild # Generate native code
Component Structure
typescript
// Mobile component template
import { View, Text, TouchableOpacity, StyleSheet } from 'react-native';
interface Props {
title: string;
onPress: () => void;
}
export function MyComponent({ title, onPress }: Props) {
return (
<TouchableOpacity onPress={onPress} style={styles.container}>
<Text style={styles.text}>{title}</Text>
</TouchableOpacity>
);
}
const styles = StyleSheet.create({
container: {
padding: 16,
backgroundColor: '#007AFF',
borderRadius: 8,
},
text: {
color: '#FFFFFF',
fontSize: 16,
fontWeight: '600',
},
});
Platform-Specific Code
typescript
import { Platform } from 'react-native';
// Conditional rendering
{Platform.OS === 'ios' && <IOSComponent />}
{Platform.OS === 'android' && <AndroidComponent />}
// Platform-specific values
const height = Platform.select({
ios: 44,
android: 56,
default: 50,
});
// Platform-specific styles
const styles = StyleSheet.create({
container: {
...Platform.select({
ios: { shadowColor: '#000', shadowOpacity: 0.3 },
android: { elevation: 4 },
}),
},
});
Best Practices
- •Performance: Use
StyleSheet.create(), avoid inline styles, optimize images - •Accessibility: Add
accessibilityLabelandaccessibilityRole - •Responsive: Test on different screen sizes
- •Navigation: Use React Navigation or Expo Router
- •State: Keep component state minimal, use context/store for shared state
Common Patterns
Lists
typescript
import { FlatList } from 'react-native';
<FlatList
data={items}
keyExtractor={(item) => item.id}
renderItem={({ item }) => <ItemComponent item={item} />}
/>
Forms
typescript
import { TextInput } from 'react-native';
const [value, setValue] = useState('');
<TextInput
value={value}
onChangeText={setValue}
placeholder="Enter text"
style={styles.input}
/>
Loading States
typescript
import { ActivityIndicator } from 'react-native';
{loading ? <ActivityIndicator /> : <Content />}
Troubleshooting
- •Metro won't start: Clear cache with
npx expo start --clear - •Native module error: Run
npx expo prebuild --clean - •Build fails: Check
app.jsonconfiguration - •Simulator issues: Reset simulator or emulator