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

Script	Purpose
scripts/mobile_scaffold.py	Scaffold project for react-native, ios, android, or flutter
scripts/build.py	Build automation with environment and platform flags
scripts/store_metadata.py	Generate App Store / Play Store listing metadata
scripts/profile.py	Profile rendering, memory, and startup performance

---

Platform Decision Matrix

Aspect	Native iOS	Native Android	React Native	Flutter
Language	Swift	Kotlin	TypeScript	Dart
UI Framework	SwiftUI/UIKit	Compose/XML	React	Widgets
Performance	Best	Best	Good	Very Good
Code Sharing	None	None	~80%	~95%
Best For	iOS-only, hardware-heavy	Android-only, hardware-heavy	Web team, shared logic	Maximum code sharing

---

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

Document	Path
React Native Guide	references/react_native_guide.md
iOS Patterns	references/ios_patterns.md
Android Patterns	references/android_patterns.md
App Store Guide	references/app_store_guide.md
Full Code Examples	REFERENCE.md

---

Troubleshooting

Problem	Cause	Solution
App crashes on launch after adding a new dependency	Incompatible native module version or missing pod install / gradle sync	Run npx pod-install (iOS) or cd android && ./gradlew clean (Android). Verify dependency version compatibility in the changelog.
FlatList renders blank or flickers	Missing keyExtractor, unstable keys, or inline renderItem causing full re-renders	Add a stable keyExtractor, wrap renderItem in useCallback, and supply getItemLayout for fixed-height rows.
iOS build fails with "signing" error	Provisioning profile mismatch or expired certificate	Open Xcode > Signing & Capabilities, select the correct team and profile. Run security find-identity -v -p codesigning to verify certificates.
Android build OOM during dexing	Insufficient JVM heap for large projects	Add org.gradle.jvmargs=-Xmx4096m to gradle.properties. Enable dexOptions { javaMaxHeapSize "4g" } in build.gradle.
App Store rejection for missing privacy manifest	Apple requires PrivacyInfo.xcprivacy for apps using required reason APIs (UserDefaults, file timestamp, etc.)	Add a PrivacyInfo.xcprivacy file declaring each required reason API. Run store_metadata_generator.py to review privacy label guidance.
Slow cold start time (>3 seconds)	Too many synchronous operations on the main thread at launch, large bundle size, or unoptimized images	Defer non-critical initialization, lazy-load modules, compress images, and use app_performance_analyzer.py to identify bottlenecks.
Hot reload / fast refresh stops working	Syntax error in a module boundary, anonymous default export, or class component state	Check terminal for error messages, ensure named exports, and restart the Metro bundler or Flutter daemon with a cache clear.

---

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 senior-backend and senior-fullstack skills).
• CI/CD pipeline configuration for mobile builds and automated distribution (see senior-devops and release-orchestrator skills).
• UI/UX design systems, accessibility auditing, or design token management (see senior-frontend and design-auditor skills).
• Runtime profiling with native tools (Xcode Instruments, Android Studio Profiler) -- the analyzer performs static code analysis only, not live device profiling.

---

Integration Points

Skill	Integration	Data Flow
senior-frontend	Shared component patterns, styling conventions, and responsive design principles for React Native web targets	Frontend design tokens and component APIs feed into mobile UI components
senior-backend	API contract definitions, authentication flows, and data models consumed by mobile clients	Backend OpenAPI specs define mobile service layer interfaces
senior-devops	Build pipelines, code signing automation, and deployment workflows for mobile releases	Mobile build artifacts flow into CI/CD pipelines for TestFlight / Play Console distribution
senior-qa	Test strategy alignment, device matrix coverage, and E2E testing patterns for mobile screens	QA test plans drive device coverage; mobile scaffold includes test directory structure
senior-security	Secure storage patterns (Keychain/Keystore), certificate pinning, and data encryption for mobile apps	Security requirements inform Keychain helper implementation and network client configuration
release-orchestrator	Version bumping, changelog generation, and coordinated release across iOS and Android	Release metadata and version info flow from orchestrator into store submission workflow

---

Tool Reference

mobile_scaffold.py

Purpose: Scaffold a production-ready mobile project with proper directory structure, navigation setup, state management, and base configuration files.

Usage:

python scripts/mobile_scaffold.py <name> --platform <platform> [options]

Parameters:

Parameter	Type	Required	Default	Description
name	positional	Yes	--	Project name, used as the directory name
--platform, -p	choice	Yes	--	Target platform: android-native, flutter, ios-native, react-native
--typescript, -t	flag	No	False (auto-enabled for react-native)	Use TypeScript (React Native only)
--state, -s	string	No	none	State management library. React Native: zustand, redux, jotai, none. Flutter: riverpod, bloc, provider, none. Not applicable for native platforms.
--output-dir, -o	path	No	. (current directory)	Parent directory for the generated project
--json	flag	No	False	Output result as JSON instead of human-readable summary

Example:

# Scaffold a React Native app with Zustand state management
python scripts/mobile_scaffold.py MyApp --platform react-native --state zustand

# Scaffold a Flutter app with Riverpod, output as JSON
python scripts/mobile_scaffold.py my-flutter-app --platform flutter --state riverpod --json

# Scaffold an iOS native app in a specific directory
python scripts/mobile_scaffold.py HealthTracker --platform ios-native --output-dir ~/Projects

Output Formats:

• Human-readable (default): Prints the project name, platform, state management choice, created directory path, and a list of all generated files.
• JSON (--json): Returns a JSON object with project_name, platform, typescript, state_management, output_directory, files_created, and generated_at fields.

---

store_metadata_generator.py

Purpose: Generate structured metadata for App Store (iOS) and Google Play Store (Android) submissions, including title variants, keywords, category recommendations, privacy labels, age rating guidance, and submission checklists.

Usage:

python scripts/store_metadata_generator.py --app-name <name> --category <category> --features <features> [options]

Parameters:

Parameter	Type	Required	Default	Description
--app-name	string	Yes	--	The app name for store listings
--category	choice	Yes	--	Primary app category. Choices: business, education, entertainment, finance, food, games, health, lifestyle, music, navigation, news, photo, productivity, shopping, social, sports, travel, utilities, weather
--features	string	Yes	--	Comma-separated list of features (e.g., "offline,sync,biometric"). Recognized features expand into keywords and trigger privacy/age-rating guidance.
--description	string	No	""	Short app description used in generated store copy
--json	flag	No	False	Output results as JSON

Example:

# Generate metadata for a health app
python scripts/store_metadata_generator.py --app-name "FitTrack" --category health --features "workout,tracking,social" --description "Track your workouts"

# JSON output for CI integration
python scripts/store_metadata_generator.py --app-name "BudgetPal" --category finance --features "payment,offline,biometric,push" --json

Output Formats:

• Human-readable (default): Formatted report with sections for Title Variants, Keywords (with iOS 100-char field), Store Categories, Privacy Labels / Data Safety, Age Rating Guidance, and Submission Checklist.
• JSON (--json): Full metadata object including titles, keywords, categories, descriptions, privacy_labels, age_rating, screenshot_specs, and submission_checklist.

---

app_performance_analyzer.py

Purpose: Analyze a mobile project directory for common performance issues including oversized image assets, re-render patterns, memory leak patterns, bundle size estimation, and platform-specific anti-patterns.

Usage:

python scripts/app_performance_analyzer.py <project_dir> [options]

Parameters:

Parameter	Type	Required	Default	Description
project_dir	positional	Yes	--	Path to the mobile project directory to analyze
--platform, -p	choice	No	Auto-detected	Target platform: react-native, flutter, ios-native, android-native. Auto-detected from project files if omitted.
--json	flag	No	False	Output results as JSON

Example:

# Analyze with auto-detected platform
python scripts/app_performance_analyzer.py ./my-app

# Analyze a React Native project explicitly
python scripts/app_performance_analyzer.py ./my-app --platform react-native

# JSON output for CI pipeline integration
python scripts/app_performance_analyzer.py ./my-app --platform flutter --json

Output Formats:

• Human-readable (default): Performance score (0-100 with letter grade), issue summary (critical/warning/info counts), bundle size estimate, detailed issues grouped by category, and platform-specific recommendations.
• JSON (--json): Full report object including performance_score, summary, bundle_estimate (source code size, asset size, file counts), issues_by_category, and the flat issues array with category, severity, file, line, and message per issue.