What Mobile Engineers Actually Do
What They Build
Booking Flow
Multi-step forms with calendar, maps, and real-time availability.
Dashboard
Data visualization, tables, and real-time transaction monitoring.
Design Editor
Collaborative canvas with WebGL rendering and multiplayer cursors.
Messaging UI
Rich text editor with threading, uploads, and emoji picker.
Mobile Engineering spans multiple platforms and approaches:
Native iOS Development
Building apps specifically for Apple devices:
- Swift development - Modern iOS development language
- UIKit/SwiftUI - UI frameworks for iOS interfaces
- Core Data - Local data persistence
- App Store submission - Navigating Apple's review process
- iOS-specific features - Push notifications, in-app purchases, ARKit
Native Android Development
Building apps for Android devices:
- Kotlin/Java - Android development languages (Kotlin preferred)
- Jetpack Compose - Modern Android UI framework
- Room Database - Local data persistence
- Google Play submission - Navigating Google's review process
- Android-specific features - Background services, widgets, Material Design
Cross-Platform Development
Building apps that work on both iOS and Android:
- React Native - JavaScript/TypeScript framework (Facebook)
- Flutter - Dart framework (Google)
- Xamarin - C# framework (Microsoft)
- Trade-offs - Code reuse vs. platform-specific optimization
Mobile Architecture
Designing scalable mobile applications:
- MVVM/MVP/MVI - Architecture patterns for maintainability
- State management - Redux, MobX, Bloc (Flutter)
- Dependency injection - Managing dependencies cleanly
- Testing - Unit tests, UI tests, integration tests
Performance Optimization
Ensuring apps run smoothly:
- Memory management - Avoiding leaks, optimizing allocations
- Network optimization - Caching, request batching, offline support
- Battery optimization - Background task management
- App size - Minimizing download and storage footprint
App Store Operations
Managing app lifecycle:
- Release management - Staged rollouts, A/B testing
- Analytics - User behavior, crash reporting, performance metrics
- User feedback - Reviews, ratings, support integration
- Compliance - Privacy policies, accessibility, platform guidelines
Skill Levels
Junior Mobile Engineer
- Implements features following established patterns
- Basic understanding of platform APIs
- Needs guidance on architecture decisions
- Can debug common issues with help
Mid-Level Mobile Engineer
- Designs features independently
- Understands platform-specific best practices
- Optimizes performance proactively
- Handles app store submissions
Senior Mobile Engineer
- Architects mobile applications
- Sets technical standards and patterns
- Makes build vs. buy decisions
- Mentors other engineers
- Balances native vs. cross-platform trade-offs
What to Look For by Use Case
iOS-Focused
Building exclusively for Apple devices:
- Priority skills: Swift, SwiftUI/UIKit, iOS design guidelines
- Interview signal: "Design an iOS app architecture for X feature"
- Certifications: Not required, but iOS development experience is essential
Android-Focused
Building exclusively for Android:
- Priority skills: Kotlin, Jetpack Compose, Material Design
- Interview signal: "How would you handle Android fragmentation?"
- Experience: Understanding of different Android versions and devices
Cross-Platform Focus
Building for both platforms with shared code:
- Priority skills: React Native OR Flutter, platform-specific modules
- Interview signal: "When would you use native modules vs. cross-platform code?"
- Trade-offs: Understanding when to go native vs. cross-platform
Performance-Critical Apps
Games, video, or resource-intensive applications:
- Priority skills: Native development, performance profiling, optimization
- Interview signal: "How would you optimize an app that's using too much memory?"
- Experience: Past performance optimization work
Consumer Apps
Apps with millions of users:
- Priority skills: Scalability, analytics, A/B testing, crash reporting
- Interview signal: "How would you handle a feature rollout to 10M users?"
- Experience: App store operations, user feedback management
Common Hiring Mistakes
1. Requiring Both iOS and Android Expertise
Most mobile engineers specialize in one platform (iOS OR Android) or cross-platform. Requiring both native iOS AND native Android is unrealistic. Cross-platform engineers know both platforms but use frameworks.
2. Overweighting Framework Experience
React Native vs. Flutter vs. native is a choice, not a requirement. Strong mobile engineers learn new frameworks in 2-3 months. Test for mobile concepts: performance, offline handling, platform patterns.
3. Ignoring App Store Experience
App store submission, review processes, and release management are critical skills. Candidates who've only built apps but never published them lack real-world experience.
4. Not Testing Performance Awareness
Mobile apps run on constrained devices. Candidates who don't think about memory, battery, or network are red flags. Ask about performance optimization examples.
5. Confusing Mobile with Web
Mobile development has unique constraints: offline scenarios, push notifications, background processing, app lifecycle. Web developers need significant retraining.
Interview Approach
Technical Assessment
- Code review - Review mobile code (Swift, Kotlin, React Native, or Flutter)
- Architecture design - "Design the architecture for a mobile app that does X"
- Performance debugging - "This app is slow/crashing. Walk me through debugging."
- Platform knowledge - Platform-specific APIs, design guidelines, limitations
Experience Deep-Dive
- Past apps - What have they built? What scale? App store ratings?
- Platform-specific challenges - iOS vs. Android differences they've encountered
- Performance optimization - Examples of optimizing memory, battery, network
- App store experience - Release processes, dealing with rejections
Cross-Platform vs. Native
- Trade-offs - When would they choose native vs. cross-platform?
- Platform modules - How do they handle platform-specific features?
- Code sharing - What code can be shared? What must be platform-specific?