Becoming a professional iOS developer is not complete without cracking interviews. In 2025, employers expect more than coding skills — they look for mastery in Swift, SwiftUI, SwiftData, concurrency, ARKit, AI integration, design patterns, security practices, and App Store publishing.
At CuriosityTech.in, we prepare learners not just for technical rounds but also for problem-solving, system design, and soft skills. Below is a comprehensive set of interview questions & answers (50+), preparation strategies, and mistakes to avoid.
1. Core Swift & Language Fundamentals
Q1. What are Optionals in Swift? Why are they important?
- Optionals represent a variable that may or may not hold a value.
- String? means the variable can contain a String or nil.
- Mandatory for safe programming in iOS (no null pointer exceptions like Java).
Q2. Explain Structs vs Classes in Swift.
- Structs → Value types, stored in stack, copied when passed.
- Classes → Reference types, stored in heap, shared references.
- Structs are preferred for lightweight models, immutability, while Classes are used for complex inheritance and reference semantics.
Q3. What are Property Wrappers?
- Custom wrappers around properties that add behavior.
- Example: @State, @AppStorage in SwiftUI.
- Used to reduce boilerplate and make declarative state management possible.
Q4. Explain Swift Concurrency (async/await, Task, Actor).
- async/await allows asynchronous code without completion handlers.
- Task defines concurrent work.
- Actor isolates mutable state, preventing race conditions.
- Mandatory in 2025 as all Apple APIs adopt async.
Q5. Difference between escaping and non-escaping closures?
- Non-escaping closure: Executed immediately, within function scope.
- Escaping closure: Executed later (e.g., network callback), stored outside function.
2. iOS Frameworks & Architecture
Q6. What is SwiftUI and why is it replacing UIKit?
- Declarative UI framework.
- Cross-platform (iOS, macOS, visionOS, watchOS).
- SwiftUI + SwiftData + async/await = future of Apple development.
Q7. How does SwiftData differ from Core Data?
- SwiftData is modern persistence, introduced in iOS 17.
- Uses @Model classes and integrates directly with SwiftUI.
- No boilerplate contexts.
Q8. Explain MVVM architecture in SwiftUI.
- Model: Data/business logic.
- ViewModel: Exposes observable data (@Observable).
- View: Declares UI bound to ViewModel.
- Mandatory architecture for SwiftUI projects.
Q9. How do NavigationStack and NavigationSplitView work in SwiftUI?
- NavigationStack: Linear navigation, supports deep linking.
- NavigationSplitView: Multi-column navigation for iPad/macOS.
Q10. What is Combine and is it still relevant in 2025?
- Combine is Apple’s reactive framework.
- Replaced by Swift Concurrency for most use cases.
- Still relevant for legacy apps.
3. Networking & APIs
Q11. How does URLSession work?
- Used for making HTTP requests.
- Supports async/await in Swift 5.5+.
Q12. Explain Codable in Swift.
- Protocol for encoding/decoding models to/from JSON/XML.
- Example: JSONDecoder().decode(User.self, from: data).
Q13. How do you secure API calls in iOS?
- Use HTTPS with SSL Pinning.
- Store tokens in Keychain, never UserDefaults.
- Use OAuth 2.0 for authentication.
4. Storage & Data
Q14. What are differences between UserDefaults, SwiftData, and Keychain?
- UserDefaults: Simple preferences/settings.
- SwiftData: Structured persistence with models.
- Keychain: Secure storage for passwords/tokens.
Q15. Explain CloudKit and its use.
- Apple’s iCloud-based database.
- Provides user-specific, device-synced storage.
- Example: Notes, Reminders apps.
5. AR, AI, and Emerging Trends
Q16. What is ARKit and RealityKit?
- ARKit → Motion tracking, plane detection, AR anchors.
- RealityKit → Rendering engine for AR objects.
Q17. How does Core ML integrate with iOS apps?
- Use .mlmodel files for predictions.
- Works offline, privacy-focused.
- Example: Image classification, NLP, recommendation systems.
Q18. How does visionOS affect iOS developers?
- Apps can now target spatial experiences.
- SwiftUI code can be extended to visionOS.
- AR/VR familiarity is now a career differentiator.
6. Testing & Deployment
Q19. What is XCTest vs Swift Testing?
- XCTest → legacy unit/UI testing.
- Swift Testing (2024+) → modern, Swift-native testing framework.
Q20. How do you publish an app on App Store?
- Enroll in Apple Developer Program.
- Configure App ID, certificates, provisioning profile.
- Archive in Xcode → Upload to App Store Connect.
- Review by Apple → Release.
7. Security & Performance
Q21. How do you secure sensitive data in iOS apps?
- Use Keychain.
- Avoid storing in UserDefaults or plain text.
- Encrypt using CryptoKit.
Q22. How do you improve app performance?
- Optimize memory leaks with Instruments.
- Use lazy loading for images.
- Avoid blocking main thread (use async).
- Test across devices.
8. Practical & Scenario-based
Q23. How would you design a Chat App?
- SwiftUI + Firebase (Realtime DB/Firestore).
- Authentication (OAuth/Firebase).
- Push notifications (APNs).
- Concurrency with async.
Q24. How would you debug layout issues?
- Use Xcode preview & View Debugger.
- Inspect Auto Layout constraints.
- Adjust priorities & compression resistance.
Q25. How do you handle backward compatibility?
- Use #available(iOS 16.0, *).
- Graceful degradation for older devices.
9. Interview Preparation Tips
- Hands-on > Theory – Build projects that demonstrate real-world skills.
- Revise Swift Fundamentals – Optionals, closures, structs vs classes.
- Master SwiftUI + SwiftData – Expected by every company in 2025.
- Know App Store Guidelines – Many fail at interview questions on publishing.
- Practice LeetCode-style problems – Arrays, strings, trees (for algorithm rounds).
- Prepare System Design Basics – Especially for senior roles (e.g., designing scalable chat apps).
- Stay Updated with WWDC – Employers expect awareness of the latest Apple frameworks.
10. Common Mistakes to Avoid
- Ignoring concurrency and async/await (deal-breaker in 2025).
- Using UIKit only (shows outdated knowledge).
- Weak knowledge of App Store publishing process.
- Poor security practices (e.g., storing tokens in UserDefaults).
- Not testing apps on different devices/orientations.
- Over-focusing on coding, under-focusing on communication skills.
Conclusion
Interviews for iOS developers in 2025 demand breadth and depth. You must demonstrate solid Swift foundations, modern frameworks (SwiftUI, SwiftData, Core ML, ARKit), concurrency, and App Store readiness. Employers want developers who can deliver secure, performant, future-ready apps across Apple’s ecosystem.
At CuriosityTech.in, we prepare you holistically: from technical mastery to interview simulations, portfolio building, and communication training. Whether aiming for your first job or advancing to senior developer roles, this roadmap and Q&A set ensures you’re industry-ready.
