---
name: ck-mobile-development
description: Build mobile apps with React Native, Flutter, Swift/SwiftUI, Kotlin/Jetpack Compose. Use for iOS/Android development, mobile UX patterns, offline-first architecture, and app store deployment.
---

# Mobile Development

Production-ready mobile development across React Native, Flutter, Swift, and Kotlin.

## When to Use

- Building iOS, Android, or cross-platform mobile apps
- Implementing mobile-first UX (offline-first, push notifications, deep linking)
- Making native vs cross-platform framework decisions
- Optimizing battery, memory, network for mobile constraints
- Deploying to App Store or Google Play

## Don't Use When

- Building responsive web apps (use web frameworks instead)
- Desktop applications (use Electron or native desktop frameworks)
- Simple PWAs that don't require native capabilities

## Framework Selection

| Need | Choose |
|------|--------|
| JavaScript team, web code sharing | React Native |
| Performance-critical, complex animations | Flutter |
| Maximum iOS performance, latest features | Swift/SwiftUI |
| Maximum Android performance, Material 3 | Kotlin/Compose |
| Rapid prototyping | React Native + Expo |
| Gaming / heavy graphics | Native or Unity |

## Performance Targets

- Launch: <2s (70% abandon if >3s)
- Memory: <100MB typical screens
- Frame rate: 60 FPS (16.67ms/frame)
- App size: <50MB initial download
- Battery: <5% drain/hour active use

## Architecture Patterns

- **Small-medium apps:** MVVM
- **Enterprise:** MVVM + Clean Architecture
- **State:** Zustand (React Native), Riverpod 3 (Flutter), StateFlow (Android)
- **Sync:** Offline-first with hybrid push/pull

## Security (OWASP Mobile Top 10)

- OAuth 2.0 + JWT + Biometrics for auth
- Keychain (iOS) / KeyStore (Android) for secrets
- Certificate pinning for network security
- Never hardcode credentials or API keys

## Testing Strategy

- Unit tests: 70%+ coverage for business logic
- E2E: Detox (React Native), XCUITest (iOS), Espresso (Android)
- Real device testing mandatory before release

## Platform Guidelines

**iOS (HIG):** Tab bar, navigation bar, San Francisco font, safe areas, haptic feedback

**Android (Material 3):** Bottom nav, FABs, Roboto font, Material You dynamic colors, ripple effects

## Deployment

- Fastlane for automation
- Staged rollouts: Internal → Closed → Open → Production
- CI/CD saves ~20% development time

## Common Pitfalls

1. Testing only on simulators (real devices show true performance)
2. Ignoring platform conventions
3. No offline handling
4. Hardcoded credentials
5. Skipping accessibility (excludes 15%+ of users)

## Resources

- React Native: https://reactnative.dev/
- Flutter: https://flutter.dev/
- iOS HIG: https://developer.apple.com/design/human-interface-guidelines/
- Material Design 3: https://m3.material.io/
- OWASP Mobile: https://owasp.org/www-project-mobile-top-10/