---
title: iOS Developer Interview Questions & Answers (2026)
description: The iOS developer interview questions that get asked in 2026 — the view controller lifecycle, SwiftUI vs UIKit, architecture, memory and concurrency — with clear answers.
url: https://usegreenroom.app/blog/ios-developer-interview-questions
last_updated: 2026-06-20
---

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# iOS developer interview questions and answers

June 19, 2026 · 10 min read

![iOS developer interview questions and answers — cover from Greenroom, the AI mock interviewer](/assets/blog/ios-developer-interview-questions-hero.webp)

iOS interviews test Apple-platform fundamentals — the view controller lifecycle, SwiftUI vs UIKit, architecture patterns, ARC memory management, and concurrency with GCD. Here are the **iOS developer interview questions** that actually get asked. (See also our Swift guide.)

## Lifecycle & UI

- The **view controller lifecycle** (viewDidLoad, viewWillAppear…).
- **SwiftUI vs UIKit** — declarative vs imperative.
- Auto Layout and constraints.
- How do you navigate between screens?
- Delegates vs closures vs notifications for communication.

## Architecture & memory

- **MVC** vs MVVM vs VIPER in iOS.
- ARC and **retain cycles** — weak vs unowned (our Swift guide).
- Value vs reference types (struct vs class) in app design.
- Memory management best practices.

![iOS interview topics — view controller lifecycle, SwiftUI, UIKit, ARC, GCD](/assets/blog/pool-structured-screen.webp)

iOS rounds test the VC lifecycle, SwiftUI/UIKit, and ARC memory management.

## Concurrency & data

- Grand Central Dispatch (GCD) — main vs background queues.
- async/await in modern Swift concurrency.
- Networking with URLSession; Codable for JSON.
- Core Data / persistence basics.

**The core truth:** iOS interviews reward knowing the view controller lifecycle and memory management cold — avoiding retain cycles and keeping UI work on the main thread are the signals of a developer who's shipped real apps.

## How to prepare

iOS rounds probe lifecycle, architecture, and memory verbally. Practise explaining retain cycles and the VC lifecycle out loud. Greenroom runs spoken technical interviews that follow up on your reasoning. Pair it with our Swift guide.

## Frequently asked questions

### What are the most common iOS interview questions?

Common iOS questions cover the view controller lifecycle, SwiftUI vs UIKit, Auto Layout, navigation, communication patterns (delegates, closures, notifications), architecture (MVC, MVVM, VIPER), ARC and retain cycles (weak vs unowned), value vs reference types, Grand Central Dispatch and Swift concurrency, URLSession networking, Codable, and Core Data.

### What is the difference between SwiftUI and UIKit?

UIKit is the older, imperative framework where you build and mutate views and manage the view hierarchy directly, offering fine-grained control and maturity. SwiftUI is the modern declarative framework where you describe the UI as a function of state and the framework updates it automatically, enabling less code and live previews. Many apps mix both, and interviewers often ask when to choose each.

### What is a retain cycle in iOS and how do you avoid it?

A retain cycle occurs when two objects hold strong references to each other (commonly a view controller and a closure that captures self), so neither is deallocated, causing a memory leak. You avoid it by using weak references (which become nil when the object is freed) or unowned references in closure capture lists, typically with [weak self].

### How should I prepare for an iOS interview?

Master the view controller lifecycle, SwiftUI and UIKit, architecture patterns, and ARC memory management (especially avoiding retain cycles), plus GCD and Swift concurrency. Practise explaining retain cycles and the lifecycle out loud with a voice-based mock interview that follows up, since these rounds probe real shipping experience over syntax.

iOS rounds reward knowing the lifecycle and memory cold, out loud. Greenroom runs spoken technical interviews that follow up on your reasoning. Free to start.