Apple iOS Developer Interview Questions (2026)

1. 1

   Why this iOS team at Apple, and what would you want to build here?

   Mid-level

   What they're checking: Whether you know which app or framework the team owns. Apple's iOS teams each set their own process and hire for their own product.

   A strong answer: Name the team and product from the posting, one thing about its user experience you'd want to improve, and the work of yours closest to it. Keep the love of Apple products to a sentence.

   Common miss: A general answer about Apple's design culture that would fit any team.

   Likely follow-up: “What would you change first in this team's app?”

   Show how to answer

“Tell me about yourself”, “Why here?” and the other common questions, and how to prep each →

1. 1

   Tell me about a time you had to debug a complex issue that was affecting users in production

   Senior

   What they're checking: How you debug when it matters: from user reports to a root cause, using evidence. Debugging is the core of several reported technical rounds.

   A strong answer: STAR. Describe the symptom and how many users it hit, how you reproduced it (crash logs, Instruments, added logging), the root cause, the fix, and what you added so it couldn't return unnoticed.

   Common miss: Jumping to the fix without showing how you proved the cause.

   Likely follow-up: “How did you know the fix worked for users, not just on your device?”

   Show how to answer
2. 2

   Walk me through a time when you had to collaborate with designers to implement a complex UI feature

   Mid-level

   What they're checking: Whether you can turn a design into a working interface and push back with evidence when something won't work. The postings ask for user-interface programming experience.

   A strong answer: STAR. Describe the design, the hard part (animation, layout across sizes, accessibility, performance), how you prototyped it, what you negotiated with the designer, and how the result held up.

   Common miss: A story where you simply built what was specified, with no trade-off discussed.

   Likely follow-up: “What did you push back on, and what did you concede?”

   Show how to answer

The six topics behind behavioral questions, and how to prep a story for each →

1. 1

   This app crashes intermittently. Find and fix the data race.

   Senior

   What they're checking: Practical concurrency debugging. A senior candidate reports technical rounds built around finding and fixing a data race or deadlock in an app.

   A strong answer: Reproduce it, then use Thread Sanitizer to find the conflicting accesses. Explain why they race, then fix it at the right level: isolate the state in an actor, confine it to one queue, or make it immutable. Rerun to show it's gone.

   Common miss: Wrapping everything in DispatchQueue.main.async until the crash stops, without understanding it.

   Likely follow-up: “Your fix moves work onto the main thread. What's the cost?”

   Show how to answer
2. 2

   Add a feature to this existing app without breaking what's there.

   Mid-level

   What they're checking: How you work in someone else's codebase: reading before writing, fitting its patterns, and testing. Candidates report rounds that ask you to extend an app's behavior.

   A strong answer: Read the relevant code paths first and say how the app is structured. Propose the change in the codebase's own style, make it in small steps, and check it in the simulator as you go. Call out anything you'd refactor with more time.

   Common miss: Rewriting the parts you don't like instead of delivering the feature.

   Likely follow-up: “How would you test this change?”

   Show how to answer
3. 3

   Explain the difference between strong, weak, and unowned references in Swift. How do retain cycles happen?

   Mid-level

   What they're checking: Memory management basics, which Apple's iOS postings name among preferred skills.

   A strong answer: ARC frees an object when its strong count reaches zero. weak is optional and becomes nil; unowned assumes the object outlives the reference and crashes if it doesn't. Show the classic cycle, a closure capturing self strongly, and how to find it with the Memory Graph debugger.

   Common miss: Using unowned everywhere as a cheaper weak, without knowing when it crashes.

   Likely follow-up: “When would you deliberately keep a strong reference to self in a closure?”

   Show how to answer
4. 4

   How do async/await and actors change the way you write concurrent iOS code?

   Mid-level

   What they're checking: Modern concurrency. The Apple Games posting prefers experience with Combine and async/await and with concurrency concepts.

   A strong answer: async/await makes asynchronous code read in order and propagates errors and cancellation. Actors isolate mutable state so only one task touches it at a time, and @MainActor keeps UI updates on the main thread. Mention reentrancy at suspension points and checking for cancellation.

   Common miss: Assuming an actor makes everything inside it atomic across an await.

   Likely follow-up: “An actor method awaits a network call halfway through. What can go wrong?”

   Show how to answer
5. 5

   What's the difference between a view's frame and its bounds?

   Entry-level

   What they're checking: UIKit fundamentals. A 2025 candidate was told to expect UIKit-specific questions in the screen.

   A strong answer: frame is the view's position and size in its superview's coordinates; bounds is its own coordinate space. Show how a transform changes the frame but not the bounds, and how changing bounds.origin scrolls content, as UIScrollView does.

   Common miss: Saying they're the same thing unless the view is rotated, with no example.

   Likely follow-up: “Why shouldn't you read frame after applying a rotation transform?”

   Show how to answer
6. 6

   A list stutters when scrolling. How would you find and fix the problem?

   Senior

   What they're checking: Performance work with tools, not guesses. The Apple Games posting prefers experience profiling and optimizing UI performance with Instruments.

   A strong answer: Measure first with Instruments: Time Profiler and the hitches or animation tools. Typical causes are main-thread work in cell setup, image decoding at full size, and expensive layout. Fix the biggest cost (downsample and decode off the main thread, cache sizes, reuse cells) and measure again.

   Common miss: Listing optimizations from memory without profiling which one matters.

   Likely follow-up: “The hitch only happens on the oldest supported device. What changes?”

   Show how to answer

1. 1

   Design a Swift API that other teams will use to fetch and display a user's data.

   Senior

   What they're checking: API design for other engineers. The Apple Games posting prefers experience designing and maintaining public APIs used by other teams.

   A strong answer: Start from the callers' needs. Use clear names, async functions or an AsyncSequence for updates, typed errors, and value types for the data. Plan for caching, cancellation and testing with a protocol-based mock, and say how you'd evolve it without breaking callers.

   Common miss: Exposing internal types and threading details that callers then depend on.

   Likely follow-up: “A caller needs a field you didn't expose. How do you add it safely?”

   Show how to answer

System design questions grouped by the concept they test, with a full walkthrough →