Swift, SwiftUI and UIKit
Prepare for the Swift, SwiftUI and UIKit rounds of an iOS interview: concurrency and isolation, memory, state and identity, and what each question scores.
Books and interactive practice
iOS interview prep
A senior iOS loop rarely fails on syntax. It fails on the second question: the actor that is not isolated the way you said, the view that re-renders because of where you put the state, the cache you sized by count instead of cost.
What the iOS loop scores
| Round | What the interviewer writes down |
|---|---|
| Swift and concurrency | Whether you can explain isolation, Sendable and cancellation from a real bug, not recite the definitions. |
| SwiftUI and UIKit | State ownership, identity and what triggers a body evaluation; when you would still reach for UIKit. |
| Architecture | Module boundaries, dependency direction, and the cost of the pattern you chose on a team of more than three people. |
| Mobile system design | Offline behaviour, sync, caching and lifecycle constraints that a backend design round never asks about. |
| Live coding | Narration, incremental progress and recovery while someone watches your screen. |
Loops differ by company. This is the common shape of senior loops, not a promise about any one employer.
The second question
Follow-ups that decide the round
“You said the view model is @MainActor. What happens to the network call inside it?”
Tests whether you know isolation applies to the function, not the work it awaits.
“The list stutters on an iPhone 11. Where do you look first?”
Tests whether you measure before you change anything, and whether you know what Instruments shows.
“Two teams want to share this module. What changes?”
Tests whether your architecture survives a second owner.
How to prepare, by the time you have
A week or less
Triage: the high-frequency questions and the follow-ups they lead to. Say every answer out loud once.
Two to four weeks
The whole loop once: Swift and concurrency, SwiftUI state, architecture, then one design scenario end to end.
Live round scheduled
Record one 45-minute task, narrated, and score the recording before anything else.
Prepare by round
The same rounds appear on every platform. Each page says what the round scores and which guides go deep.
Architecture
Prepare for the mobile architecture round on iOS, Android and Flutter: module boundaries, dependency direction, state ownership and defending your pattern.
Mobile system design
Prepare for the mobile system design round: offline behaviour, sync, caching, lifecycle and release, and what the interviewer scores at Senior and Staff.
Coding and live coding
Prepare for mobile coding, live coding and pair programming rounds: the tasks that recur, how they are graded, and what to say while you type.
Senior and Staff
What changes in a Senior or Staff mobile interview loop: the follow-up depth, the scope of the design round, and the evidence each level is expected to show.
iOS interview guides
iOS · 12 min
Apple iOS mock interview: a practice loop for 2026
An Apple iOS mock interview built honestly: what Apple's careers pages publish (little), a Swift-heavy practice loop, seven practice prompts and a rubric.
iOS · 14 min
iOS architecture interview questions: defending a decision
Ten iOS architecture interview questions and how senior answers are scored: MVVM, TCA, navigation, dependency injection, SPM modules, testing.
iOS · 12 min
iOS coding interview: the tasks and how they are graded
What an iOS coding interview asks: the practical tasks that recur, the algorithm round in Swift, and what is graded beyond whether it compiles.
iOS · 18 min
iOS interview questions in 2026, round by round
iOS interview questions for 2026, organised by round: Swift, concurrency, memory, SwiftUI, UIKit, architecture, system design, testing, coding and behavioural.
iOS · 13 min
iOS mock interview: a full round you can run in 2026
A complete iOS mock interview you can run alone or with a partner: timing, eight prompts with follow-ups, a scoring rubric and how to self-score a recording.
iOS · 11 min
iOS technical interview: the rounds and what each scores
What an iOS technical interview loop contains, what each round scores, and where strong Swift candidates still lose it.
iOS · 16 min
Senior iOS interview questions for 2026, and the follow-ups
Twelve senior iOS interview questions for 2026: what each scores, a weak and a senior answer, and the follow-up on Swift 6 concurrency, SwiftUI, architecture.
iOS · 15 min
Senior iOS mock interview: a full loop for 2026
A senior iOS mock interview loop: four 45 to 60 minute rounds, escalating follow-ups, senior versus mid-level answers, a rubric and a debrief template.
iOS · 13 min
Swift interview questions and answers, as they are scored
Swift interview questions with spoken answers: value and reference types, protocols, generics, memory and errors, and the follow-up each one leads to.
iOS · 13 min
SwiftUI interview questions and what they score
SwiftUI interview questions on identity, state ownership, Observation and performance, each with the answer that scores, the trap and the follow-up.
iOS · 14 min
Top 10 iOS interview questions for 2026
The top 10 iOS interview questions in 2026, with what each one scores, a weak answer, a senior answer and the follow-up that separates the two.
iOS · 30 min
Top 100 iOS interview questions with answers (2026)
The top 100 iOS interview questions for 2026 with short answers, grouped by area: Swift, memory, concurrency, SwiftUI, UIKit, architecture, design and testing.
iOS · 24 min
Top 50 iOS interview questions and answers (2026)
The top 50 iOS interview questions for 2026, grouped by area, with what each question scores and a senior answer: Swift, concurrency, SwiftUI, UIKit and more.
iOS · 12 min
UIKit interview questions still asked in 2026
UIKit interview questions that still appear in iOS loops: lifecycle, layout passes, cell reuse, diffable data sources, and UIKit with SwiftUI.
Across platforms
Mobile system design · 17 min
Mobile system design interview: how the round is scored
How a mobile system design round runs, the seven things a senior answer covers, a worked offline sync example, and how Senior and Staff are scored.
Senior and Staff loops · 11 min
Mobile architecture interview questions, any platform
Architecture interview questions that do not depend on the platform: modules, shared code, server-driven UI, flags, old app versions and who owns what.
Live coding · 14 min
Mobile live coding interview: what to say while you type
How a mobile live coding round is scored, a 45-minute plan, what to say at each stage, a worked Swift example, and how to recover when you stall.
Practice
More books for the iOS loop
Not sure which one? iOS interview books compares them by the time you have left.