Swift iOS Interview Questions 2025 – Topic wise

A well-organized set of iOS interview questions curated from real interview experiences and industry practices — grouped by topic for quick access and effective preparation.

1. Swift Basics

What is the difference between var and let?
What are Optionals in Swift and how do you unwrap them?
What is optional chaining?
What is a Tuple in Swift?
What is the difference between Struct and Class?
What is a computed property?
What are property observers (willSet, didSet)?
What is a lazy property?
What are access control levels in Swift?
What is the difference between guard and if let?
What are extensions in Swift?
What are the different collection types (Array, Set, Dictionary)?
Difference between static and class functions?

2. Memory Management

What is ARC (Automatic Reference Counting)?
What is a memory leak?
What is a retain cycle and how can you avoid it?
What is the difference between weak and unowned?
How do you detect memory leaks using Instruments?

3. Architecture & Code Design

Explain MVC, MVVM, and VIPER architecture.
What architecture have you used in your recent project and why?
How do you implement Dependency Injection in Swift?
What is protocol-oriented programming?
How do you structure a modular iOS codebase?

4. Closures & Protocols

What is a closure in Swift?
What is an escaping closure? How is it different from non-escaping?
What is a delegate pattern?
Difference between Delegation and NotificationCenter?
What are protocols and protocol extensions?

5. Networking & APIs

What is URLSession and how does it work?
What is a completion handler?
How do you handle API errors in your app?
How do you decode nested JSON using Codable?
What are background downloads and how do you handle them?

6. Concurrency & Async Programming

What is GCD (Grand Central Dispatch)?
Difference between serial and concurrent queues?
How do DispatchGroup, DispatchSemaphore, and NSOperationQueue work?
What is Swift Concurrency (async/await)?
How is Swift Concurrency better than GCD?
What is thread safety and how do you ensure it?

7. UIKit & UI Development

Difference between frame, bounds, and center?
Lifecycle of a UIViewController?
Difference between viewDidLoad, viewWillAppear, and viewDidAppear?
How does Auto Layout work?
How do you implement pagination in UITableView or UICollectionView?

8. SwiftUI

What are the main differences between SwiftUI and UIKit?
How does data flow in SwiftUI (State, Binding, ObservedObject, Environment)?
How do you handle performance in SwiftUI for large lists?
What are ViewModifiers and why are they useful?

9. App Lifecycle & System Integration

What is the role of AppDelegate and SceneDelegate?
What is the app lifecycle from launch to termination?
What are background modes in iOS?
How do you handle push notifications?
How do background tasks work (silent push, BGTaskScheduler)?

10. Persistence & Local Storage

How does UserDefaults work and what are its limitations?
How do you choose between Core Data and Realm?
How do you implement offline storage/caching?
What is the difference between synchronous and asynchronous Core Data fetches?

11. Security & Privacy

How do you store sensitive user data in iOS?
What is Keychain and when should it be used?
How do you prevent reverse engineering of your iOS app?
What are the security threads in API ? How can we avoid it?

12. Testing, CI/CD, and Deployment

How do you write unit tests in iOS?
How do you mock network calls for testing?
What is XCUITest and how does it work?
How do you distribute apps via TestFlight?
What are app thinning and on-demand resources?

Final Thoughts

Whether you’re preparing for your first iOS interview or your fifth, focusing on topics instead of random question lists gives you a clearer learning path. Bookmark this page and revisit often — we’ll keep it updated!

Bonus

Want a downloadable PDF version of these categorized questions? Drop a comment or message and we’ll send it your way!

Be confident and crack your next round fast! 🚀