When I was seeking my first job, I was in the dark on how to prepare for interviews. After facing countless rejections and spending hours unproductively, I’ve learned the art of preparing effectively. Here’s how I do it.

Types of Problems for iOS Interviews

Interviews can throw various types of problems your way:

  1. Data Structures & Algorithms (mostly encountered in medium to large-sized companies)
  2. Take-Home Assignments (common in small to medium-sized companies)
  3. Phone/Video Technical Screen (present in almost all companies)
  4. Onsite (including problem-solving, whiteboarding, pair programming, bug squash, code review)

Key Areas of Focus for iOS Interviews

Let’s discuss key areas you should focus on:

Fundamentals

While the depth of knowledge required varies by role, a strong command over Swift & iOS is crucial. Here are some advanced examples:

  • Explain the difference between struct and class in depth, including when to use one over the other.
  • Discuss how memory is managed in iOS, focusing on reference cycles and memory leaks.
  • Explain the lifecycle of an iOS app and how different components interact during the lifecycle.

Networking

Advanced iOS interviews will test your ability to fetch, manage, and display data:

  • Design and implement a robust networking layer that can handle various types of HTTP requests (GET, PUT, POST, PATCH, DELETE).
  • Discuss the best practices for handling data received from the server and converting it into usable formats.

Data Storage

Understanding data persistence is essential:

  • Discuss different strategies for storing images downloaded from a server, weighing the pros and cons of each.
  • Share your thoughts on Core Data, UserDefaults, or other storage options.

UI

UI questions are omnipresent and might require you to demonstrate your understanding of:

  • Advanced usage of Auto Layout, including dealing with complex layouts and dynamic content.
  • Best practices for using TableView and CollectionView, including optimization techniques.
  • Considerations for creating a responsive and fluid UI.

Design Patterns/Architecture

Having a good grasp of different design patterns and architectures is crucial:

  • Discuss the pros and cons of MVC, MVVM, and other architectural patterns.
  • Talk about how you would architect a complex feature or app module, considering things like testability, maintainability, and scalability.

System Design

Although not exclusive to iOS, system design is becoming increasingly important:

  • How would you design a feature like Uber’s ride request system on the iOS client side?
  • Discuss how you would approach building an offline-first iOS app.
  • How would you manage and synchronize local and server data?

Communication

Effective communication is key. Stay vocal throughout the interview, even if you’re stuck. Your thought process can provide valuable insights to the interviewer and may even lead them to give hints to move forward.

Navigating iOS interviews can be tough. With this guide, I hope to make it a little easier for you. For more tips, download my free interview cheat sheet!