18Software Engineering · Interview Prep · Free
iOS Developer interview questions — and how to answer them.
These are the questions iOS Developer candidates are most likely to face, from openers to the hard ones — each with a note on what a strong answer covers. Want more, tuned to your level? Use the free generator below.
What interviewers look for in a iOS Developer
- Concrete examples of systems you've built, with the trade-offs you weighed
- How you debug — the process, not just the fix
- Collaboration signals: code review, disagreements, mentoring
Likely iOS Developer interview questions
1. Walk us through your experience with iOS development. What versions of iOS have you worked with, and what was your most recent project?
Demonstrate hands-on experience with Swift/Objective-C, specific iOS versions, and concrete project examples with measurable outcomes.
2. Can you explain the difference between Swift and Objective-C? When would you choose one over the other?
Show understanding of both languages' strengths, syntax differences, and practical scenarios where each is more appropriate.
3. What is the View Controller lifecycle in iOS, and why is it important?
Accurately describe viewDidLoad, viewWillAppear, viewDidAppear, viewWillDisappear, viewDidDisappear and explain when to use each.
4. How do you handle memory management in iOS? Explain ARC and potential pitfalls.
Discuss Automatic Reference Counting, retain cycles, weak references, and demonstrate awareness of common memory leaks.
5. Describe your approach to handling network requests and parsing JSON responses in iOS.
Cover URLSession, error handling, background tasks, and familiarity with REST APIs and modern async patterns like async/await.
6. What's your experience with Core Data or other local persistence solutions? How do you handle database migrations?
Explain CRUD operations, entity relationships, fetch requests, and demonstrate knowledge of versioning and migration strategies.
7. Tell us about a bug you encountered in iOS development. How did you debug and resolve it?
Show systematic debugging methodology using Xcode debugger, logging, breakpoints, and explain the root cause clearly.
8. How do you ensure your iOS apps are responsive and performant? What tools do you use for profiling?
Mention Instruments (Memory, CPU, Core Animation), optimize rendering, main thread blocking awareness, and battery efficiency considerations.
9. Explain your experience with reactive programming in iOS. Have you used RxSwift, Combine, or similar frameworks?
Demonstrate understanding of Observables/Publishers, subscription management, and practical benefits in real-world scenarios.
10. How do you implement unit testing and UI testing in iOS? Walk us through a testing strategy for a feature.
Cover XCTest framework, mocking/stubbing, test organization, coverage goals, and the balance between unit and integration tests.
11. Describe your approach to architecting a large iOS app. What design patterns do you favor and why?
Discuss MVVM, VIPER, or other patterns, dependency injection, separation of concerns, and how you'd structure a scalable codebase.
12. Tell us about a time you disagreed with a design or technical decision. How did you handle it and what was the outcome?
Show diplomatic communication, data-driven reasoning, willingness to compromise, and focus on team/product success over ego.
Want to practice answering live with scored feedback? Try the Mock Interview Coach. Applying too? See a iOS Developer cover letter example.
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