Senior Mobile Developer

Expert mobile application development across iOS, Android, React Native, and Flutter.

Keywords

mobile, ios, android, react-native, flutter, swift, kotlin, swiftui, jetpack-compose, expo-router, zustand, app-store, performance, offline-first

Quick Start

# Scaffold a React Native project
python scripts/mobile_scaffold.py --platform react-native --name MyApp

# Build for production
python scripts/build.py --platform ios --env production

# Generate App Store metadata
python scripts/store_metadata.py --screenshots ./screenshots

# Profile rendering performance
python scripts/profile.py --platform android --output report.html

Tools

Platform Decision Matrix

Workflow 1: Scaffold a React Native App (Expo Router)

1. Generate project -- python scripts/mobile_scaffold.py --platform react-native --name MyApp
2. Verify directory structure matches this layout:

   src/
   ├── app/              # Expo Router file-based routes
   │   ├── (tabs)/       # Tab navigation group
   │   ├── auth/         # Auth screens
   │   └── _layout.tsx   # Root layout
   ├── components/
   │   ├── ui/           # Reusable primitives (Button, Input, Card)
   │   └── features/     # Domain components (ProductCard, UserAvatar)
   ├── hooks/            # Custom hooks (useAuth, useApi)
   ├── services/         # API clients and storage
   ├── stores/           # Zustand state stores
   └── utils/            # Helpers
   

3. Configure navigation in app/_layout.tsx with Stack and Tabs.
4. Set up state management with Zustand + AsyncStorage persistence.
5. Validate -- Run the app on both iOS simulator and Android emulator. Confirm navigation and state persistence work.

Workflow 2: Build a SwiftUI Feature (iOS)

1. Create the View using NavigationStack, @StateObject for ViewModel binding, and .task for async data loading.
2. Create the ViewModel as @MainActor class with @Published properties. Inject services via protocol for testability.
3. Wire data flow: View observes ViewModel -> ViewModel calls Service -> Service returns data -> ViewModel updates @Published -> View re-renders.
4. Add search/refresh: .searchable(text:) for filtering, .refreshable for pull-to-refresh.
5. Validate -- Run in Xcode previews first, then simulator. Confirm async loading, error states, and empty states all render correctly.

Example: SwiftUI ViewModel Pattern

@MainActor
class ProductListViewModel: ObservableObject {
    @Published private(set) var products: [Product] = []
    @Published private(set) var isLoading = false
    @Published private(set) var error: Error?

    private let service: ProductServiceProtocol

    init(service: ProductServiceProtocol = ProductService()) {
        self.service = service
    }

    func loadProducts() async {
        isLoading = true
        error = nil
        do {
            products = try await service.fetchProducts()
        } catch {
            self.error = error
        }
        isLoading = false
    }
}

Workflow 3: Build a Jetpack Compose Feature (Android)

1. Create the Composable screen with Scaffold, TopAppBar, and state collection via collectAsStateWithLifecycle().
2. Handle UI states with a sealed interface: Loading, Success<T>, Error.
3. Create the ViewModel with @HiltViewModel, MutableStateFlow, and repository injection.
4. Build list UI using LazyColumn with key parameter for stable identity and Arrangement.spacedBy() for spacing.
5. Validate -- Run on emulator. Confirm state transitions (loading -> success, loading -> error -> retry) work correctly.

Example: Compose UiState Pattern

sealed interface UiState<out T> {
    data object Loading : UiState<Nothing>
    data class Success<T>(val data: T) : UiState<T>
    data class Error(val message: String) : UiState<Nothing>
}

@HiltViewModel
class ProductListViewModel @Inject constructor(
    private val repository: ProductRepository
) : ViewModel() {
    private val _uiState = MutableStateFlow<UiState<List<Product>>>(UiState.Loading)
    val uiState: StateFlow<UiState<List<Product>>> = _uiState.asStateFlow()

    fun loadProducts() {
        viewModelScope.launch {
            _uiState.value = UiState.Loading
            repository.getProducts()
                .catch { e -> _uiState.value = UiState.Error(e.message ?: "Unknown error") }
                .collect { products -> _uiState.value = UiState.Success(products) }
        }
    }
}

Workflow 4: Optimize Mobile Performance

1. Profile -- python scripts/profile.py --platform <ios|android> --output report.html
2. Apply React Native optimizations:
   • Use FlatList with keyExtractor, initialNumToRender=10, windowSize=5, removeClippedSubviews=true
   • Memoize components with React.memo and handlers with useCallback
   • Supply getItemLayout for fixed-height rows to skip measurement
3. Apply native iOS optimizations:
   • Implement prefetchItemsAt for image pre-loading in collection views
4. Apply native Android optimizations:
   • Set setHasFixedSize(true) and setItemViewCacheSize(20) on RecyclerViews
5. Validate -- Re-run profiler and confirm frame drops reduced and startup time improved.

Workflow 5: Submit to App Store / Play Store

1. Generate metadata -- python scripts/store_metadata.py --screenshots ./screenshots
2. Build release -- python scripts/build.py --platform ios --env production
3. Review the generated listing (title, description, keywords, screenshots).
4. Upload via Xcode (iOS) or Play Console (Android).
5. Validate -- Monitor review status and address any rejection feedback.

Reference Materials

Troubleshooting

Success Criteria

• App startup time under 2 seconds on cold launch (measured on mid-range devices, both iOS and Android).
• Crash-free rate above 99.5% across all supported OS versions, tracked via Crashlytics or Sentry.
• Frame rendering at 60 fps (16ms per frame) for scrolling lists and animations, with zero jank frames during typical user flows.
• Bundle size under 50 MB for the initial download (excluding on-demand resources), verified before each release.
• Performance analyzer score of 75+ (Grade B or above) when running app_performance_analyzer.py against the project.
• Zero critical issues and fewer than 5 warnings reported by the performance analyzer before submitting to app stores.
• App Store / Play Store approval on first submission with complete metadata, correct privacy labels, and proper age rating, validated using store_metadata_generator.py.

Scope & Limitations

This skill covers:

• Scaffolding production-ready mobile projects for React Native (Expo Router), Flutter, iOS native (SwiftUI), and Android native (Jetpack Compose).
• Static performance analysis including image asset sizing, re-render detection, memory leak patterns, and bundle size estimation.
• App Store and Play Store metadata generation including titles, keywords, privacy labels, age ratings, and submission checklists.
• Platform-specific architecture patterns (MVVM, state management, navigation).

This skill does NOT cover:

• Backend API development or server-side logic (see senio