iOS Developer Interview Questions

When it comes to crafting seamless, intuitive iOS applications, the right developer can be the linchpin to success. This article presents a comprehensive list of interview questions curated to help hiring managers and recruiters identify the ideal iOS developer candidate. From understanding the nuances of Apple's ecosystem to ensuring the application's performance on multiple devices, these questions are designed to gauge both the technical depth and the practical experience of your prospective hire.
What is ARC in iOS development? Answer: ARC stands for Automatic Reference Counting. It's a system that automatically manages memory, helping developers avoid memory leaks by ensuring that objects are deallocated when they're no longer in use. 2.
View answer
What are the main architectural patterns used in iOS development? Answer: The main patterns include MVC (Model-View-Controller), MVVM (Model-View-ViewModel), and VIPER. 3.
View answer
Explain the difference between strong, weak, and unowned references. Answer: Strong increases the reference count and prevents deallocation. Weak references don't increase the count and can become nil. Unowned is similar to weak but assumes the reference will never become nil. 4.
View answer
Describe the app lifecycle in iOS. Answer: The app lifecycle states include Not Running, Inactive, Active, Background, and Suspended. 5.
View answer
How does the delegation pattern work? Answer: The delegation pattern allows one object to delegate certain responsibilities or behaviors to another object, typically achieved through protocols in Swift. 6.
View answer
What's the difference between frame and bounds in iOS? Answer: Frame defines a view's location and size in its superview's coordinate system, whereas bounds describes a view's location and size in its own coordinate system. 7.
View answer
How would you handle concurrency in iOS? Answer: iOS offers several tools for handling concurrency, including Grand Central Dispatch (GCD) and NSOperationQueues. 8.
View answer
What is UIKit? Answer: UIKit is a framework in iOS that provides the necessary classes for building user interfaces, handling user input, and managing screen navigation. 9.
View answer
Explain the difference between UITableView and UICollectionView. Answer: Both are used to display lists, but UITableView is for single-column lists, while UICollectionView offers more flexibility in arranging items in multiple columns and rows. 10.
View answer
What's the purpose of the Info.plist file? Answer: It's a configuration file that contains essential metadata about the app, like its version number, display name, and required permissions. 11.
View answer
What is Core Data? Answer: Core Data is a persistence framework provided by Apple for storing data locally on devices. 12.
View answer
How is @IBOutlet different from @IBAction? Answer: @IBOutlet is a reference to a UI element, whereas @IBAction is a method that gets called when a specific UI event occurs. 13.
View answer
Describe what Auto Layout is. Answer: Auto Layout is a system that lets you lay out your app's UI by creating a series of constraints that define the UI's look and behavior. 14.
View answer
What are Swift optionals? Answer: Optionals are a way in Swift to represent the absence or presence of a value, helping avoid runtime crashes due to nil references. 15.
View answer
What is a closure in Swift? Answer: Closures are self-contained blocks of functionality that can be passed and used in your code, similar to lambdas in other languages. 16.
View answer
Describe the Singleton design pattern in iOS. Answer: Singleton ensures that a class has only one instance and provides a global point of access to that instance. 17.
View answer
How would you manage dependencies in your project? Answer: I'd use tools like CocoaPods or Swift Package Manager to manage and maintain external libraries or dependencies. 18.
View answer
What's the difference between synchronous and asynchronous tasks in iOS? Answer: Synchronous tasks block the main thread, making the UI unresponsive, while asynchronous tasks run concurrently, allowing the UI to remain responsive. 19.
View answer
What is Fastlane? Answer: Fastlane is a tool that automates building, testing, and releasing iOS apps. 20.
View answer
Explain memory cycles or retain cycles in iOS. Answer: Retain cycles occur when two objects hold strong references to each other, causing a memory leak since neither object can be deallocated. 21.
View answer
How do you optimize table views for performance in iOS? Answer: By reusing cells, keeping cell layouts simple, and prefetching data. 22.
View answer
What is a protocol in Swift? Answer: A protocol defines a set of methods and properties that a class, struct, or enum can adopt and implement. 23.
View answer
How do you handle sensitive data in iOS apps? Answer: By using the Keychain for secure storage and ensuring data in transit is encrypted using HTTPS. 24.
View answer
Explain the purpose of NotificationCenter. Answer: NotificationCenter allows objects to communicate with each other by sending and receiving events or messages without having a direct coupling. 25.
View answer
What's the difference between an extension and a category in iOS? Answer: Both allow you to add methods to
View answer

Hiring an iOS Developers With Braintrust

In your pursuit of iOS Developers, we stand ready to assist in finding top talent swiftly. With our services, you can expect to be matched with five highly-qualified iOS Developers within just minutes. Let us streamline your recruitment process and connect you with the skilled professionals you seek to meet your needs effectively.

Looking for Work

Alex Kovalyshyn

Alex Kovalyshyn

Mobile Developer
Seattle, WA
  • iOS
  • JavaScript

Looking for Work

Ana Leticia Camargos

Ana Leticia Camargos

iOS Engineer
Belo Horizonte, Brazil
  • React
  • iOS

Looking for Work

Kayla Mudny

Kayla Mudny

Sr. Mobile Engineer
Kingston, TN
  • iOS
  • Node.js

Why Braintrust

1

Our talent is unmatched.

We only accept top tier talent, so you know you’re hiring the best.

2

We give you a quality guarantee.

Each hire comes with a 100% satisfaction guarantee for 30 days.

3

We eliminate high markups.

While others mark up talent by up to 70%, we charge a flat-rate of 15%.

4

We help you hire fast.

We’ll match you with highly qualified talent instantly.

5

We’re cost effective.

Without high-markups, you can make your budget go 3-4x further.

6

Our platform is user-owned.

Our talent own the network and get to keep 100% of what they earn.

Get matched with Top iOS Developers in minutes 🥳

Hire Top iOS Developers