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. Tell us about your experience with iOS development. What versions of iOS have you worked with?
Mention specific iOS versions, frameworks (UIKit/SwiftUI), and duration of experience with concrete examples.
2. Describe a recent iOS app you built. What was your role and what technologies did you use?
Discuss architecture decisions, challenges overcome, and measurable outcomes or features delivered.
3. What's the difference between Swift and Objective-C? Which do you prefer and why?
Show understanding of both languages' strengths, when each is appropriate, and reasoning for preference.
4. Explain how MVC, MVVM, or MVP architectures work. Which have you used and when?
Demonstrate knowledge of separation of concerns, testability, and trade-offs between patterns.
5. How do you handle asynchronous operations in iOS? Walk us through your approach with async/await or callbacks.
Discuss Grand Central Dispatch, DispatchQueue, async/await syntax, memory management, and avoiding deadlocks.
6. Describe your experience with networking in iOS. How do you handle API requests and error handling?
Cover URLSession, REST principles, JSON decoding, error strategies, and retry logic.
7. How do you manage state and pass data between ViewControllers or SwiftUI views?
Discuss delegates, notifications, dependency injection, @State, @ObservedObject, and when to use each.
8. Tell us about your experience with Core Data or other persistence solutions. How do you handle migrations?
Explain CRUD operations, fetching strategies, threading considerations, and versioning/migration approaches.
9. How would you approach debugging a memory leak in an iOS app? Walk through your process.
Mention Instruments, Xcode debugger, retain cycles, weak references, and specific tools like Allocations.
10. Describe your testing strategy for iOS apps. What tools and frameworks do you use?
Cover XCTest, unit testing, UI testing, mocking, dependency injection, and test coverage goals.
11. How do you optimize app performance and startup time? Give specific examples.
Discuss lazy loading, caching strategies, profiling with Instruments, main thread safety, and code splitting.
12. Design a scalable architecture for a large iOS app with multiple teams. How would you organize code and dependencies?
Address modularization, dependency management (CocoaPods/SPM), separation of layers, code reusability, and team collaboration patterns.
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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