Apple iOS mock interview: a practice loop for 2026

An Apple iOS mock interview has an honest problem at its centre: Apple publishes almost nothing about how it interviews engineers. I read Apple’s careers pages before writing this. They describe how the company is organised and point to job search. I did not find a published description of the interview process, the number of rounds, or what is assessed. Anyone who tells you “the Apple loop is exactly this” is repeating secondhand accounts.

So this page does not pretend. It says what Apple’s pages do say, then gives you a mock loop for a senior iOS engineer that is built around the one thing you can be sure of: if you interview for an iOS role anywhere, Apple included, you will be tested on Swift, the frameworks and how you build for the platform. It has seven practice prompts with follow-ups and the rubric I use when I write up a candidate.

The prompts are practice prompts I wrote. They are generic iOS engineering problems, not questions Apple has asked. I never attribute a question to a named company, on this page or anywhere on this site.

What Apple publishes, and what it does not

As described on Apple’s careers pages, Apple organises around functional expertise, with experts leading experts in each area, and the pages direct candidates to job search for open roles. That is context and does not describe the interview. It may mean that the people interviewing you for an iOS role are specialists in that area, though the page does not say so.

What I could not find on Apple’s own pages:

• A description of the stages of the engineering interview process
• The number or length of interviews
• Whether coding happens in an IDE, a document or on a whiteboard
• Any list of topics or an assessment rubric

Third-party sites describe Apple loops in detail, but I am not citing them, because I cannot verify them against anything Apple has published. The practical advice is the same as for any company: ask your recruiter for the format of your specific loop, including the number of rounds, whether any round is a take-home or a project discussion, and what the technical rounds focus on. Teams at a large company can run very different loops for the same title.

Why the mock is built the way it is

Without a published format, I built the mock from what an iOS role demands, not from rumor. That means Swift fluency, including Swift concurrency under the Swift 6 language mode, framework knowledge across SwiftUI and UIKit, performance and memory on a real device, privacy and permissions, and app-level design. It also means a conversation about past work, because every senior loop I have been part of includes one.

The mock is heavier on Swift and platform detail than the general FAANG mobile mock interview. If your recruiter describes something different, reshape the rounds to match and keep the rubric.

The mock loop at a glance

This is a practice shape I built, not an Apple loop. Apple publishes no round structure, so treat every row as an assumption to check with your recruiter.

If you do not know whether you will have Xcode, practise round 1 both ways. Writing Swift without the compiler exposes gaps in things like optional handling and protocol syntax that the IDE normally hides.

Round 1: Swift coding

Prompt 1: a generic LRU cache in Swift

Write a generic cache with a fixed capacity where keys are Hashable. Reading a value marks it as most recently used; inserting past capacity evicts the least recently used entry.

Follow-ups: Why a class for the list nodes and not a struct? Where could a retain cycle appear in your linked list, and how do you avoid it? How would you make this safe to use from multiple tasks?

What a strong answer shows: a dictionary from key to node plus a doubly linked list, weak or unowned on one direction of the links with the reason stated, O(1) reads and writes, and a concurrency answer that picks an actor and accepts that every call becomes await, or picks a lock and explains why the synchronous API matters to callers.

Prompt 2: parse and validate a feed payload

Given a JSON payload of posts where some fields may be missing or malformed, decode it into model types so that one bad post does not fail the whole feed.

Follow-ups: Where do you report the bad posts? What if the server adds a new post type next month? How do you test this?

What a strong answer shows: Codable with a lossy wrapper or a per-element decode that collects failures, an unknown case for forward compatibility, and tests driven by JSON fixtures including a broken element.

In both prompts, I score idiomatic Swift. Value types where they fit, clear optional handling, no force unwraps without a reason said out loud. A solution that works but reads like translated Java loses points on a senior iOS bar.

Round 2: Swift concurrency and the platform

Prompt 3: a search screen with cancellation

Build the model behind a search screen: debounce typing, cancel stale requests, never show results for an older query, and keep the UI updates on the main actor.

Follow-ups: Under the Swift 6 language mode, what does the compiler now reject that Swift 5 mode only warned about? If the response type is not Sendable, what happens? Where exactly does cancellation reach the network call?

What a strong answer shows: a stored Task cancelled on each change, a sleep that throws on cancellation used as the debounce, a check that the result matches the current query, a @MainActor model, and a clear explanation that data-race checks become errors under Swift 6 mode. The candidate should know that URLSession’s async methods respond to task cancellation.

Prompt 4: an image pipeline that respects memory

A photo grid shows thousands of thumbnails from the photo library. Scrolling stutters and memory climbs. Walk through how you find the cause and what you change.

Follow-ups: Which Instruments templates do you open first? Where does decoding happen today? How do you size images for the cell rather than the original?

What a strong answer shows: measuring before changing (Time Profiler for the stutter, Allocations for the growth), downsampling to the display size, decoding off the main thread, a cache sized in bytes with a response to memory warnings, and prefetching that is cancelled when cells scroll away.

This round is where a senior iOS candidate should sound like someone who has shipped. I listen for tool names, specific numbers they would look at, and the order in which they would try things.

Round 3: app design

Prompt 5: background photo backup

Design a feature that backs up the user’s new photos to a server, including large videos, without the user keeping the app open.

Follow-ups: What happens when the app is suspended or terminated mid-upload? How do you avoid uploading the same file twice? What permissions do you need, and what happens if the user grants only limited library access?

What a strong answer shows: a background URLSession configuration for large transfers that continue while the app is suspended, a persisted queue of pending uploads with stable identifiers for idempotency, handling of the limited photo library access case, and a clear stance on battery and cellular data. The privacy follow-up should be answered as a product decision as well as an API one.

Prompt 6: a settings screen shared by SwiftUI and UIKit

The app is mostly UIKit. A new settings area will be built in SwiftUI and must share state with existing UIKit screens. Design the state flow.

Follow-ups: Where does the state live? How does a UIKit screen observe a change made in SwiftUI? How would you migrate the rest over time without a rewrite?

What a strong answer shows: a single observable model owned outside both view layers, UIHostingController at the boundary, observation from UIKit through a published stream or the observation framework, and an incremental migration plan screen by screen with a rule for new work.

Design answers on an iOS loop should stay close to the device. Server architecture is fine to mention. The interviewer wants to hear about what the app does when the network, the OS or the user does something inconvenient.

Round 4: past work and judgement

Prompt 7: a quality call you made

Tell me about a time you pushed back on shipping something because the quality was not there. What happened?

Follow-ups: Who wanted to ship, and why? What evidence did you bring? If you were overruled, what did you do? Would you make the same call today?

What a strong answer shows: a specific feature, a specific quality problem with evidence (a crash rate, a performance number, an accessibility failure), the conversation that followed, and the result. Candidates who were overruled and handled it well often give the best answers here.

I write down whether the story would be different if the candidate had not been there. If it would not, the story is about the team, not about them.

The rubric

Score each round from 1 to 4 on these rows, with one line of evidence each.

For a senior iOS bar, look for 3s everywhere with at least one 4 in platform depth or concurrency. A 1 anywhere is the next thing to fix.

How to run it

• Ask your recruiter about format first, and adjust the rounds if it differs.
• Keep the prompts from yourself: your partner reads this page, you do not.
• Run round 1 once in Xcode and once in a plain document.
• Record, replay the first five minutes, and fix the lowest row before the next run.

The replay usually shows the same thing: the candidate knew the answer and did not say the reason. The reason is what gets scored.

What changed in 2024 to 2026

• Swift 6.2 shipped on 15 September 2025 with what the Swift team calls approachable concurrency (Swift.org, Swift 6.2 released).
• A module can opt in to main actor isolation by default, so its code runs on the main actor without @MainActor written on every type.
• The new @concurrent attribute marks a function that should run concurrently, which makes it visible in the code when work leaves the actor.

Sources

• Apple Careers, Work at Apple
• Apple Jobs, Search roles
• Swift.org, Migrating to Swift 6
• The Swift Programming Language, Concurrency
• Apple Developer, Downloading files in the background
• Apple Developer, Delivering an enhanced privacy experience in your photos app
• Swift.org, Swift 6.2 released

The Apple careers pages were read on 24 September 2026 and did not describe the interview process. If Apple publishes one later, it replaces everything in the section about what Apple publishes.

What to do next

• Senior iOS interview questions, for the depth behind rounds 1 and 2
• iOS system design interview, for round 3
• iOS coding interview, for Swift coding practice
• Practice, to run the prompts under a timer

Run the whole loop once before you change anything, so you have an honest baseline. Then fix one row at a time.