Lead with tradeoffs, not buzzwords
Interviewers reward clear comparisons—when to use actors vs queues, diffable data sources vs manual updates, async/await vs completion handlers—and why it matters in production.
Practice iOS interviews with questions worth your time
Work through realistic prompts on concurrency, UIKit, SwiftUI, and how systems fit together—written for engineers preparing for phone screens, loops, and senior-level conversations.
How to use this site
Pick a topic or browse the full catalog. Open a question for a deeper write-up with code where it helps. Use the exercise on each card to practice explaining your answer out loud or on paper—same rhythm as the interview room.
Questions across Swift, SwiftUI, UIKit, and architecture—the topics that show up in real iOS and iPadOS interviews.
Each card gives you a tight summary, talking points for how to answer, and a small exercise so you rehearse instead of skimming.
Filter by topic, difficulty, or tag when you want to drill one area before a loop or on-site.
What we emphasize
The habits that separate strong iOS candidates
Tie answers to real app behavior
Expect to connect APIs to scrolling, memory, threading, and state. The goal is to sound like someone who has shipped and debugged iOS apps, not someone who only read release notes.
Practice out loud
Use the short exercises on each card to rehearse how you would walk through a problem on a whiteboard or in a live-coding session.
Featured Questions
Questions to start with
What problems does diffable data source solve, and what does it not solve?
Show where UIKit snapshot-based updates help and where state modeling still matters
Key points
- Cover safe animated updates and reduction of index-path bookkeeping bugs.
- Explain that identity modeling still matters because unstable identifiers create visual glitches.
- Mention performance implications for very large snapshots and frequent churn.
Practice
Design identifiers for a feed with ads, loading placeholders, and server-driven cards, then describe snapshot update rules.
When would you choose a Swift actor over a serial DispatchQueue?
Compare language-level isolation with traditional queue-based synchronization in production iOS code
Key points
- Explain actor isolation and how it prevents data races at the type-system level.
- Contrast that with a serial queue protecting mutable state through convention.
- Call out interoperability, reentrancy, and when legacy APIs still justify queues.
Practice
Refactor a cache manager that uses a private queue so writes become actor-isolated and reads remain ergonomic.
How do task groups differ from async let in practical iOS code?
Explain when fixed child tasks make `async let` the better tool, and when dynamic fan-out or incremental result handling pushes you to task groups
Key points
- Frame `async let` as the best fit for a small, fixed number of child tasks that are obvious in the current scope.
- Explain task groups as the structured-concurrency tool for dynamic fan-out, result streaming, and policies like limited result collection or manual cancellation.
- Mention that both are structured concurrency, then separate them by ergonomics, workload shape, and how explicitly you need to manage results.
Practice
You first fetch a feed payload, then discover 40 image URLs, but the screen only needs the first 12 decoded thumbnails to render quickly. Describe whether you would use `async let` or a task group, how you would cancel extra work, and what tradeoffs you would mention in an interview.
Topics
Learn by area
Swift
Core Swift language rules and reasoning patterns that frequently appear in iOS interviews before the discussion narrows into UI or concurrency specifics
2 questions · Value vs reference semantics, immutability, ownership, optionals, and API design
Concurrency
Modern Swift concurrency, synchronization tradeoffs, and the reasoning interviewers expect around safety and performance
3 questions · Actors, structured concurrency, cancellation, data-race prevention
UIKit
Collection and table view architecture, rendering performance, and classic UIKit tradeoffs still common in production codebases
2 questions · Diffable data sources, cell identity, rendering pipelines, view-controller design
SwiftUI
State ownership, view identity, data flow, and interoperability decisions for modern Apple platform teams
2 questions · Property wrappers, dependency flow, lifecycle, compositional UI design