iOS Developer Interview Questions (2026) and How to Answer
By FindAJobAI team Updated How we wrote this page
iOS interviews almost always include a Swift coding round, often focused on memory management or concurrency, plus a discussion of how you'd structure an app's architecture. Many add a take-home project or a live exercise building a small screen against a mock API.
Below: 30 questions with what each one really asks and an answer outline, full sample answers to the 10 most asked, red flags to avoid and a 7-day plan.
Answering with STAR
Tell each story in four steps: the situation in a sentence, your task, the actions you took (most of the answer) and the result, with a number if you have one. Aim for about two minutes; the outlines show what to include, the details must be yours.
Behavioural questions (1–10)
How you've handled real situations. Answer each with one true story, in STAR order.
1.Tell me about a feature you shipped from design handoff to the App Store.
What they're really asking: Can you carry a feature through design, build, testing and release without losing scope?
Answer outline (STAR)
- SituationA designer handed off a redesigned checkout screen with several new states.
- TaskTurn the mockups into a working feature ready for review and release.
- ActionBreak the screen into components, confirm edge cases with the designer, build it behind a flag, and write unit tests for the view model.
- ResultThe feature shipped on schedule, and the flag let support turn it off quickly if needed.
Full sample answer (fictional example)
When our checkout redesign came from design, it had five new states: empty cart, promo applied, error, loading and success. I broke the screen into smaller view models so each state could be tested on its own, and flagged two edge cases with the designer before building, like a promo expiring mid-checkout. I built it behind a feature flag so we could turn it off instantly if something went wrong after launch. It shipped on schedule, and we removed the flag after two weeks with no crash reports tied to it.
2.Tell me about a time your app crashed in production and you had to fix it fast.
What they're really asking: Can you diagnose a live crash under pressure without making the problem worse?
Answer outline (STAR)
- SituationA crash spiked right after a Friday release, hitting about 4 percent of sessions on one iOS version.
- TaskFind the cause and ship a fix before the weekend made support's queue worse.
- ActionPull the crash logs and symbolicate the stack trace, reproduce it on the affected OS version, and patch the nil check that caused it.
- ResultThe fix went out as a hotfix release within six hours, and the crash rate returned to normal.
Full sample answer (fictional example)
A Friday release caused a crash affecting about 4 percent of sessions on iOS 17 only. I pulled the crash logs from our dashboard and symbolicated the stack trace, which pointed to an unguarded nil value in a new analytics call. I added the missing check, wrote a quick test so it couldn't regress, and we submitted an expedited review request to Apple explaining the crash. The fix went live within six hours of the first report, and the crash rate dropped back to its normal baseline by the next morning.
3.Tell me about a disagreement with a designer over how a screen should behave.
What they're really asking: Can you push back on a design respectfully using platform conventions as evidence?
Answer outline (STAR)
- SituationA designer wanted a custom swipe gesture that conflicted with the system's back-swipe behavior.
- TaskFind a version that kept the designer's intent without confusing users used to iOS conventions.
- ActionPrototype both versions, test the custom gesture against the Human Interface Guidelines, and show the designer the conflict on a real device.
- ResultWe agreed on a modified gesture that avoided the conflict, and it shipped without complaints about navigation.
Full sample answer (fictional example)
A designer wanted a custom swipe gesture on a detail screen that conflicted with the system's edge swipe for going back. I built both versions and tested them on a real device. I showed the designer how the custom gesture fought with the back-swipe, which confused even me at first. We agreed on a version that used a button instead of a full-screen swipe, keeping the motion the designer wanted. It shipped without navigation complaints, and the designer now checks the Human Interface Guidelines before proposing a gesture.
4.Tell me about a time you missed an SLA and what you did about it.
What they're really asking: Checks whether you own a miss honestly instead of explaining it away.
Answer outline (STAR)
- SituationA high-priority ticket sat past our four-hour response target because of a queue misconfiguration.
- TaskResolve the ticket and the trust it cost without making excuses to the customer.
- ActionApologized plainly, gave a real timeline for the fix, and flagged the queue bug to our ops team the same day.
- ResultThe customer accepted the timeline and stayed, and the queue bug was fixed before it caused a second miss.
5.Tell me about getting an app rejected by App Review and what you did next.
What they're really asking: Can you navigate App Review without losing patience or missing the actual guideline?
Answer outline (STAR)
- SituationA submission was rejected for using a private API that a third-party library called internally.
- TaskRemove the violation and resubmit without delaying the release by more than a few days.
- ActionTrace the call to the library, replace it with a public alternative, and write a clear note to the reviewer explaining the fix.
- ResultThe resubmission was approved within a day, and we added a check to catch private API use earlier.
Full sample answer (fictional example)
We were rejected for using a private API that turned out to be called internally by a third-party analytics library, not by our own code. I traced the crash report and binary symbols to confirm which library was responsible, then found a public replacement with the same functionality. I rewrote the small piece of code that depended on it and tested the change on a clean device before resubmitting. The resubmission was approved within a day, and we added a build check that flags private API symbols before any future submission.
6.Tell me about mentoring a junior developer on your iOS team.
What they're really asking: Checks whether you can grow other engineers, not just write code yourself.
Answer outline (STAR)
- SituationA new grad joined the team and struggled with Swift's optional handling and app architecture.
- TaskGet them contributing confidently within the first couple of months.
- ActionPair on two features together, review their pull requests with specific suggestions, and point them to one good article per concept instead of a long list.
- ResultThey shipped their first solo feature in week six, and now review others' pull requests themselves.
7.Tell me about adopting a new Apple framework or API before it was widely used.
What they're really asking: Checks whether you evaluate new tools on fit rather than excitement alone.
Answer outline (STAR)
- SituationApple released a new async image-loading API the year before our app's next major version.
- TaskDecide whether to adopt it immediately or wait for it to mature.
- ActionPrototype one screen with it, test on the minimum supported OS version, and compare it against the existing library on performance and crash reports.
- ResultWe adopted it for new screens only, and migrated the rest over the following two releases.
8.Tell me about a time you had to say no to a feature request.
What they're really asking: Checks whether you can protect app quality under pressure from stakeholders.
Answer outline (STAR)
- SituationMarketing asked for a pop-up on every launch to promote a seasonal campaign.
- TaskProtect the app's launch experience without just refusing outright.
- ActionShow data on how similar pop-ups hurt retention in another app, and propose a smaller banner instead.
- ResultMarketing agreed to the banner, and launch-to-first-action time stayed unchanged.
9.Tell me about working with a backend team whose API didn't match what the app needed.
What they're really asking: Checks whether you can resolve mismatches with another team without stalling your work.
Answer outline (STAR)
- SituationA new endpoint returned paginated data in a shape that didn't fit the app's existing list screens.
- TaskGet the screen working without a long back-and-forth delaying the release.
- ActionWrite an adapter layer in the app to reshape the response, while filing a ticket with the backend team for the cleaner version.
- ResultThe screen shipped on time, and the backend team updated the shape two releases later without any app changes needed.
10.Tell me about a code review you gave that changed how a teammate wrote code.
What they're really asking: Checks whether you give feedback that actually improves a teammate's habits.
Answer outline (STAR)
- SituationA teammate's pull requests kept using force-unwrapped optionals that risked crashes.
- TaskChange the habit without making the reviews feel personal.
- ActionPoint to specific lines each time, explain the crash risk with an example, and share a short guide on safe unwrapping patterns.
- ResultForce-unwraps in their pull requests dropped sharply over the next month, and they started flagging them in others' code too.
Technical and role-skill questions (11–22)
Can you do the work itself? Think out loud and name the trade-offs.
11.What's the difference between a strong, weak and unowned reference in Swift?
What they're really asking: Tests whether you understand ARC well enough to avoid memory leaks and crashes.
Answer outline
- A strong reference keeps an object alive as long as the reference exists.
- A weak reference doesn't keep the object alive and becomes nil automatically when it's deallocated.
Full sample answer (fictional example)
A strong reference is the default: it keeps the object it points to alive for as long as the reference itself exists. A weak reference doesn't keep the object alive, and Swift automatically sets it to nil once the object is deallocated, which is why weak references have to be optional. An unowned reference also doesn't keep the object alive, but it never becomes nil; accessing it after the object is gone crashes, so I only use it when I'm certain it won't outlive the object.
12.How does SwiftUI's view update cycle differ from UIKit's?
What they're really asking: Checks whether you understand declarative rendering versus manual view updates.
Answer outline
- SwiftUI re-renders a view's body whenever its observed state changes, rather than you updating properties directly.
- UIKit requires you to mutate views yourself and call layout methods like setNeedsLayout when something changes.
13.Walk me through how you'd fix a retain cycle in a closure.
What they're really asking: Tests whether you can spot and resolve the most common Swift memory leak.
Answer outline
- Find the closure that captures self and is held by an object that self also holds, directly or indirectly.
- Add a capture list marking self as weak or unowned, based on whether the closure might run after self is gone.
14.How do you decide between GCD and Swift's async/await for a networking task?
What they're really asking: Checks whether you pick concurrency tools based on fit, not habit.
Answer outline
- Async/await reads more clearly for sequential work, like fetching data and then updating the UI.
- GCD still suits fine-grained queue control, such as a custom serial queue guarding shared state.
Full sample answer (fictional example)
For most networking code now, I reach for async/await first, since it reads top to bottom like synchronous code and makes error handling with try and catch straightforward. It also avoids the nested completion handlers that used to make GCD-based networking hard to follow. I still use GCD when I need fine-grained control over a queue, such as serializing writes to a shared cache from multiple places in the app. On an older codebase that's mostly GCD, I'll introduce async/await gradually at the boundaries rather than rewrite everything at once.
15.How would you persist and sync data for an app that works offline?
What they're really asking: Tests whether you can design local storage that survives conflicts and bad connections.
Answer outline
- Store data locally with Core Data or SQLite, and mark each record with a last-updated timestamp.
- Queue changes made offline and replay them when connectivity returns, resolving conflicts with a clear rule such as last-write-wins or a manual merge screen.
16.What causes an app to be rejected by App Review, and how do you avoid it?
What they're really asking: Checks whether you know the guidelines well enough to prevent delays before submission.
Answer outline
- Common causes include crashes on launch, incomplete metadata, broken links, and using private or undocumented APIs.
- Privacy issues are common too, such as missing usage descriptions or tracking without the required prompt.
17.How do you profile and fix a janky scroll in a table or collection view?
What they're really asking: Tests whether you can diagnose UI performance instead of guessing at a fix.
Answer outline
- Profile with Instruments' Time Profiler to find what's running on the main thread during scrolling.
- Move expensive work, such as image decoding or text layout, off the main thread or cache the result.
18.How do you structure a medium-sized app: MVVM, MVC, or something else?
What they're really asking: Checks whether you choose architecture based on the app's needs, not habit.
Answer outline
- MVC is fine for simple screens, but view controllers grow bloated as logic piles up.
- MVVM moves logic and state into a testable view model, which pairs well with SwiftUI's data binding.
19.How would you reduce an app's binary size if the App Store flagged it as too large?
What they're really asking: Tests whether you know the common sources of bloat in a shipped app.
Answer outline
- Check for unused assets, duplicate images at multiple resolutions, and unused third-party libraries.
- Enable App Thinning and on-demand resources so users only download what their device needs.
Full sample answer (fictional example)
I'd start by checking the App Store Connect size report to see which part of the bundle is largest, usually images or bundled frameworks. Last time, our asset catalog had unused image sets left over from an old design, and removing them alone cut several megabytes. I'd also confirm App Thinning is set up correctly so each device only downloads the slices it actually needs, rather than every resolution. For any large framework no longer in use, I'd check with the team before removing it, then measure the size again before resubmitting.
20.What's your approach to writing unit tests for view models in a SwiftUI app?
What they're really asking: Checks whether you test logic in a way that survives UI changes.
Answer outline
- Keep the view model free of UIKit or SwiftUI types so it can be tested without rendering anything.
- Test state transitions directly: given this input, the published property should end up in this state.
21.How do you handle background tasks like downloads that need to survive app suspension?
What they're really asking: Tests whether you understand iOS's background execution limits and the APIs for them.
Answer outline
- Use a background URLSession configuration so the download continues even if the app is suspended or killed.
- Handle the completion in the app delegate callback the system provides when the task finishes.
22.How do you store sensitive data such as an auth token securely on device?
What they're really asking: Checks whether you know where secrets belong instead of defaulting to UserDefaults.
Answer outline
- Store tokens in the Keychain, not UserDefaults or plain files, since Keychain entries are encrypted at rest.
- Set an appropriate accessibility level, such as requiring the device to be unlocked.
Take-home or live exercise: tips
Expect a live Swift round building a small screen, or a take-home project.
- Commit in small steps so your thinking is visible, rather than one final commit.
- Handle loading, empty and error states, not just the happy path.
- Leave a short README noting trade-offs you made under the time limit.
Situational questions (23–30)
Scenarios that test judgement: say what you'd do first, and why.
23.QA finds a crash the night before a release is due to ship. What do you do?
What they're really asking: Checks whether you can triage a late-breaking crash without panicking the whole team.
Answer outline
- Reproduce the crash first and confirm how many users it would actually affect.
- Decide with the team whether to fix and re-test, revert the change, or delay the release by a day.
Full sample answer (fictional example)
First I'd reproduce the crash myself and check how many users the affected path would actually reach, since not every late crash deserves panic. Last time, it only hit a rarely used settings screen, so we fixed it, added a test, and shipped on time after a short regression pass. If the fix had touched a core flow like checkout, I'd have pushed to delay a day instead of rushing a risky patch through. Either way, I'd tell the release manager and QA lead the decision and the reasoning immediately.
24.A designer wants an animation that will hurt battery life on older devices. How do you handle it?
What they're really asking: Checks whether you can balance design ambition against real device constraints.
Answer outline
- Measure the actual cost on an older device rather than guessing how bad it is.
- Offer a simplified version for older or low-power-mode devices instead of flatly refusing the idea.
25.Your app's crash rate spikes after a third-party SDK update. What's your next step?
What they're really asking: Tests whether you isolate blame correctly before reacting to a vendor's change.
Answer outline
- Confirm the spike actually correlates with the update using crash reports and version numbers.
- Pin the SDK to the last known-good version while you investigate, rather than leaving users exposed.
Full sample answer (fictional example)
I'd confirm the spike actually lines up with the SDK update by checking crash reports against the app version and the SDK version embedded in each build. Once that was confirmed, I'd pin the dependency back to the last stable version rather than leave users on a crashing build while we investigated further. I'd report it to the vendor with our crash logs and a minimal reproduction, and check their issue tracker. Only once they shipped a fix would I upgrade again, testing it in a beta build first.
26.Product wants a feature shipped in two days that usually takes two weeks. How do you respond?
What they're really asking: Checks whether you can negotiate scope honestly instead of promising something impossible.
Answer outline
- Break the feature into the smallest version that still delivers real value.
- Say plainly what fits in two days and what would be cut or faked for the demo.
27.A user reports a bug you can't reproduce on any device you have. What do you do?
What they're really asking: Checks whether you can investigate a hard-to-reproduce issue methodically.
Answer outline
- Ask for their exact device model, iOS version, and the steps they took, since small differences often matter.
- Check crash and analytics logs for anything matching their account or device around that time.
Full sample answer (fictional example)
I'd start by getting their exact device model, iOS version and the precise steps they took, since small differences like a specific locale or an older OS version often explain bugs I can't see. I'd also check our crash and analytics logs for anything tied to their account or timestamp that might point to the cause. If that didn't turn up anything, I'd add targeted logging around the area they described and ship it in the next release so we'd catch it if it happened again.
28.Apple changes a privacy requirement mid-release cycle. How do you adjust the project?
What they're really asking: Tests whether you can absorb an external compliance change without derailing the release.
Answer outline
- Read the actual requirement change rather than relying on secondhand summaries.
- Scope the change to what's legally required for this release, and push nice-to-have improvements to the next one.
29.Your team is split between SwiftUI and UIKit for a new feature. How do you decide?
What they're really asking: Checks whether you make architecture calls on evidence instead of personal preference.
Answer outline
- Check the minimum supported iOS version and whether the feature needs UIKit-only components.
- Weigh the team's current SwiftUI experience against the time pressure on this particular feature.
30.A critical bug ships to production over a weekend with nobody on call. What do you do?
What they're really asking: Tests whether you can respond to an unowned incident without clear coverage in place.
Answer outline
- Assess the actual impact first, since not every weekend bug needs an emergency fix.
- If it's serious, reach whoever can approve an emergency release and ship a hotfix.
Red flags to avoid in your answers
Each one is quick to fix before the day.
Force-unwrapping optionals everywhere instead of handling nil safely.
Explain how you'd use optional binding or guard statements, and why crash-free code matters to users.
Treating UI work as less serious than backend logic.
Talk about a UI detail you polished and why it mattered to users.
No mention of testing on real devices, only the simulator.
Describe which real devices and iOS versions you test on before release.
Blaming App Review rejections without learning the guideline that caused them.
Walk through a rejection you resolved and what you changed in the app or metadata.
How to prepare for an iOS developer interview in 7 days
An hour or two a day is enough; the order matters more than the length.
Day 1: Memory and concurrency review
Go over strong/weak/unowned references, retain cycles and the difference between GCD and async/await until you can explain each without notes.
Day 2: Swift coding drills
Solve five small Swift problems on arrays, strings and optionals under a timer.
Day 3: Architecture walkthrough
Pick one app you built and rehearse a five-minute walkthrough of its architecture, including what you'd change now.
Day 4: Crash story rehearsal
Write out your production crash fix as a STAR story and practice telling it in under two minutes.
Day 5: App Store guidelines skim
Read the App Store Review Guidelines summary for common rejection reasons: privacy, metadata and crashes on launch.
Day 6: Portfolio app polish
Fix the rough edges in your portfolio app: empty states, error handling and accessibility labels.
Day 7: Live coding simulation
Build a small screen from a mock API within 45 minutes, then explain your decisions out loud to a friend.
Questions to ask the interviewer
Pick two or three; the answers tell you whether you want the job.
- What's the current app architecture, and is the team moving toward SwiftUI or staying with UIKit?
- How does the team handle App Store review timelines when planning releases?
- What's the current crash-free rate, and which tool tracks it?
- How much of the codebase is covered by automated tests?
- What does the release cadence look like, and who owns App Store submissions?
Preparation tips
- Review Swift memory management and concurrency, since both come up in almost every technical round.
- Practice explaining a past crash fix clearly, since production debugging stories come up often.
- Skim the App Store Review Guidelines summary so rejection questions don't catch you off guard.
Prepare the general questions too: tell me about yourself, why do you want to work here? and why are you leaving? Afterwards, send a thank-you email; when the offer comes, negotiate the salary.
How we wrote this page
The FindAJobAI team wrote the questions, outlines and sample answers for iOS developer interviews. The people, employers and numbers in the samples are invented: copy the structure, and use details from your own work.
Once we track enough live iOS developer job ads, this page also shows the skills they ask for most, counted the same way as our in-demand skills report.
Last reviewed on November 1, 2026.