Meta iOS Engineer Interview Guide

This phone screen typically consists of a call with the hiring manager or recruiter. The call often starts with a brief introduction from both sides; the hiring manager might introduce themselves and their role within the company, and you'll have the opportunity to briefly introduce yourself.

The hiring manager will ask general character-based questions to gauge your personality, work ethic, and team compatibility. These questions aim to understand if you'd be a good fit for the company culture. For example:

• Tell me about yourself.
• What are your strengths and weaknesses as an iOS developer?
• Can you describe a situation where you faced a challenge in a team project and how you handled it?

They might also delve into your technical skills and knowledge of iOS development. This may include questions about iOS development frameworks, tools, and best practices. For instance:

• How familiar are you with Swift and Objective-C?
• Have you worked with any cloud platforms such as AWS or Firebase for backend integration?
• How do you approach debugging and troubleshooting issues in your iOS applications?
• Can you share an example of a challenging bug you encountered and how you resolved it?

The Initial Technical Screen interview at Facebook typically lasts for approximately 45 minutes, although the exact time breakdown may vary slightly depending on the interviewer. Here's a breakdown of what you can expect:

Introductions (5-10 minutes):

The interview begins with introductions, allowing you and the interviewer to get to know each other. During this time, your interviewer may ask questions related to your iOS knowledge and experience.

These initial questions aim to gauge your familiarity with iOS development, such as your proficiency in using key APIs and your ability to solve common iOS-related problems. For instance,

• Tell us about your experience with iOS development?
• Can you explain how you would handle memory management in an iOS app?
• Can you explain the difference between UIKit and SwiftUI in iOS app development?

It's expected that you can answer most of these questions based on your day-to-day work. 

It's important to be well-prepared for this segment, as it sets the tone for the rest of the interview, so it's always a good idea to brush up on core iOS APIs if you haven't used them recently.

Coding (25-35 minutes):

The bulk of the ITS interview is dedicated to coding problems. These coding problems are not necessarily iOS-specific but often revolve around data structures and algorithms. You may encounter one longer coding question or a series of shorter ones, designed to assess your problem-solving skills and coding abilities. 

For instance, 

• Implement a function in Swift that finds the two numbers in an array that sum up to a given target value.
• Implement a function that checks if a given string is a palindrome.

Final 5 minutes:

The last 5 minutes of the interview are reserved for your questions to the interviewer.

This segment provides an opportunity for you to learn more about Facebook, particularly from an engineering perspective. You can ask questions like 

• Can you tell me more about the day-to-day responsibilities of a software engineer on the iOS team at Meta?
• What are the current challenges the team is facing?

This is a chance to learn more about Meta from an engineering perspective and demonstrate your genuine interest.

You’re going to have 4 or 5 interviews over the course of the day. These will be distributed across three different types of interviews: Coding Interview, Design Interview, Behavioral Interview, and Questions.

Let's discuss them in detail:

The Coding Interview – 

This interview typically consists of a combination of general coding questions and iOS-specific questions. Here's how it unfolds:

• Introduction and iOS Knowledge Assessment (5-10 minutes): The interview usually starts with a brief introduction where you can get to know your interviewer. Be prepared to answer questions about your iOS knowledge and experience. These questions aim to gauge your familiarity with iOS development, key APIs, and common problem-solving in this domain.
• iOS-specific Questions: Next, expect questions related to iOS development, such as how to use essential APIs and how to tackle common challenges faced by iOS developers. These are often based on practical scenarios you might encounter in your day-to-day work.
• Coding Problems (25-35 minutes): The bulk of this interview will be dedicated to solving coding problems. You'll be presented with one or more coding challenges that assess your problem-solving and coding skills. These problems may involve data structures, algorithms, or iOS-specific development tasks. Make sure you brush up on your coding skills, review iOS development concepts, and practice problem-solving extensively.

The Design Interview

In the design interview, the focus shifts to assessing your design skills, either related to systems or product design, depending on your background. Here's what to expect:

The design interview typically lasts 45 minutes and is conversation-based, with minimal to no coding involved. You'll primarily engage in discussions and whiteboard drawings.

The interviewer will present a non-trivial engineering design problem related to systems or products. Your task is to analyze, discuss, and propose solutions to this problem. The goal is to assess your ability to think critically and design effective solutions. 

As with other interviews, you'll have the opportunity to ask questions during the final minutes of the interview. It's a chance to seek clarification or gain insights into the company and role.

It’s important to note - the iOS Design interview is a bit different from traditional “backend focused” system design. The interview you’ll face will be much more app-focused than back-end focused so it’s worth investing into preparing for them. Your interviewer is trying to understand your ability to solve a complicated iOS engineering design problem. Or in other words - can you architect a high-level solution to a problem that has multiple concepts and components. 

Have a structure and methodical approach. Our general recommendation is to split things into discrete layers starting from the View, Controller, Network, Storage, Cache, since this is how you’d design a system in real life. 

Preparation is key here, for both the design as well as coding rounds—which can get progressively challenging. So, we'd recommend practice with professionals. Prepfully has 18 iOS Engineers who help candidates with mocks. They’ve collectively helped over 500 candidates already, in the last couple of months - which means they’ve got great insight on the common mistakes to avoid, as well as advice on how to improve.

The Behavioral Interview

In this interview, you'll dive into your work history, motivations, and a series of behavioral questions. However, it's worth noting that the Facebook behavioral interview has a unique twist—it's a hybrid of behavioral and coding questions.

1. Behavioral Assessment: The first part of this interview delves into your background, resume, and motivations. You'll discuss your work history, experiences, and what drives you. The aim here is to assess if you align with Meta's engineering culture, which is known for its peer-to-peer collaboration, minimal process, and unstructured approach. So, be ready to discuss how your previous experiences demonstrate your ability to thrive in such an environment.
2. Coding Component: Surprisingly, there's a coding element in this interview as well, albeit shorter than the dedicated coding interviews. You'll face a coding question that complements the more in-depth coding assessments earlier in the day. Consider this to be another opportunity for you to demonstrate your coding skills and problem-solving abilities.

Interview Questions

• Describe a time when you had to resolve a dispute with a teammate.
• How many ways can you implement concurrency in iOS?
• What is the difference between OperationQueue and GCD?
• Implement a function in Swift that reverses a linked list. Walk me through your thought process and write the code
• Given an array of integers, write a function to find the two numbers that add up to a specific target sum. What's the time complexity of your solution, and can you optimize it further?
• Describe the architecture you would use for a chat application in iOS. How would you handle real-time messaging and synchronization between devices?
• Given two binary numbers in string format, calculate their sum.
• Find the common parent of two UIViews in a view hierarchy.
• How would you design the data flow and storage mechanisms within an iOS app, considering factors like network requests, local caching, and data persistence?
• Explain your approach to designing the user interface (UI) of X iOS app. How would you ensure a seamless and user-friendly experience?
• Given two views, write an algorithm to find the closest common superview if one exists.
• How would you design a flight booking app?
• Implement a hashmap data structure.
• Design an airline booking app.
• How would one navigate from the top left of a quad-graph to the bottom right?