mobile-development

name	mobile-development
description	Build iOS/Android apps that are performant, offline-capable, accessible, and battery-efficient
difficulty	senior
domains	["mobile"]

Overview

Mobile apps have unique constraints: unreliable networks, limited battery, strict platform guidelines, and app store review. This skill applies mobile-specific engineering discipline.

When to Use

• Before implementing a new mobile feature
• When an app is slow, crashes, or drains battery
• Before submitting to the app store

Process

Step 1: Design for offline-first

Assume the network is unavailable. Design data flows that work offline and sync when connectivity returns. Use optimistic UI updates.

Step 2: Main thread discipline

• No I/O on the main thread
• No heavy computation on the main thread
• Profile with Instruments (iOS) or Android Profiler for frame drops

Target: 60fps during all user interactions.

Step 3: Memory management

• No strong reference cycles (iOS: use weak/unowned)
• Instrument for memory leaks before release
• Release large resources when the app backgrounds

Step 4: Battery efficiency

• Minimize background work
• Batch network requests
• Use push over polling
• Reduce GPS/sensor usage frequency when precision isn't needed

Step 5: App size

• Analyze app size before each release
• Use on-demand resources for large assets
• Target: < 30MB download for initial install

Step 6: Crash rate

• Integrate crash reporting from day one (Crashlytics, Sentry)
• Fix crashes before shipping new features
• Target: < 0.1% crash-free sessions

Step 7: Accessibility

• Dynamic Type support (iOS) / font scaling (Android)
• VoiceOver (iOS) / TalkBack (Android) tested
• Touch targets ≥ 44pt × 44pt
• Color contrast meets WCAG AA

Step 8: App store compliance

• Review App Store / Play Store guidelines for relevant categories before implementing
• Test on oldest supported OS version
• Implement required privacy labels/permissions honestly

Verification Requirements

• Offline state handled gracefully
• No I/O or heavy computation on main thread
• Profiled: 60fps during interactions
• Crash reporting integrated
• Accessibility tested with platform screen reader
• App size within budget
• Tested on oldest supported OS version