The future for iOS app developers looks bright as the number of iOS users across the world is growing steadily.

Smartphone ownership has demonstrated positive year-on-year growth. Today iOS devices continue to have a loyal customer base. Innovative devices such as Apple TV and Apple Watch help to successfully retain and replenish this base.

Considering these facts, an iOS app development certification is one of the easiest ways to hone your skills in the same. 

The proper time to become an iOS developer

What an iOS developer should know?

Apple was founded in 1976 by Steve Jobs, Steve Wozniak, and Ronald Wayne. The company was officially incorporated in 1977 and experienced exponential revenue growth in its first five years. For example, in the interim 1977-1980, the company had an average annual growth rate of 533%. Nowadays Apple Inc. continues to be one of the most popular and profitable companies in the world. How many interviews does Apple do daily? We can only guess about it.

There has never been a better time to become an iOS developer! If you are going to start a career in iOS app development, this post would be helpful as here we have created a list of top frequently-asked iOS interview questions that will help you ace your iOS job interview.

We’ve tried our best to help you feel prepared for your iOS interview. Consider the questions and get some practical tips along the way! But note that the post is on a very subjective topic, where there are thousands of different opinions. We will be glad to hear your own thoughts after the reading, so do not hesitate to comment.


iOS development


How do I prepare for iOS developer interview?

Before we dive into the most relevant iOS interview questions and answers, let’s first highlight some general tips to make sure that your technical interview goes smoothly. Here’re some essential tips:

1. Outline the basics

There are no chances to prepare for every possible question, so try to just pay special attention to the basics. 

Make sure you clearly know the features of Objective-C 2.0. Logically expect the questions related to protocols, messaging, dynamic types, categories, forwarding, posing, etc. Your interviewer will probably want to see how much you are familiar with current or recent problems. Do not doubt reading over Apple’s Objective-C guides to make sure there are no topics on which you feel weak. 

Most companies have stopped asking cheesy questions, but you may want to prepare yourself for the possibility. When you are faced with these types of questions, the most important is to demonstrate your thought process.

2. Be ready for whiteboard coding

You might also be asked to perform some whiteboard coding in case of an interview is in person. Make sure you have practice in this, because, with the pressure of performing in front of someone, it may prove harder than you are expecting. Be ready to do whiteboard coding for any language you know.

3. Consider interview etiquette

Сompany’s dress code is also an essential thing you should consider before. Showing up in a suit when the interviewer is wearing shorts and a t-shirt can be embarrassing.

Silence your phone and do not answer or look at it during the interview. In case of a possible emergency situation (perhaps, the wife of the candidate may be going into labor soon) let the hiring manager know beforehand.

Make sure you are well rested mentally and physically before the interview. Try to schedule the meeting when you don’t have anything else going on. Avoid compounding the stress you will already feel.

Try to arrive 15 minutes early, for an in-person interview, but no earlier. In case of a virtual interview, sure to dial in about two minutes early.

4. Do not neglect thinking through the probable questions

Be ready with the most important questions. At the end of the interview, you will often be asked if you have any questions about the possible job, responsibilities of the company.

Be prepared for these questions and have a couple of topics written down. It will demonstrate that you are actually interested in the job and aren’t just going through the motions. After all, this is a great opportunity to learn if the job could be a good fit for you.

Top iOS Interview Questions You Must Prepare In 2021

A technical interview may last a different amount of time and has a different number of questions. Depending upon what the interviewer learns about the candidate, he/she may tailor his/her choice of questions somewhat.

What questions are asked in an Apple interview?

When answering questions, try to keep your answer brief and explain your thoughts. Remember, that interviewers aren’t asking you the questions because they don’t know the answers. They want to see if you know what you are talking about.

Now is the time you’ve been waiting for – the questions themselves!

1. Give the abbreviation of iOS. Explain it.

iOS stands for Intelligent Operating System. Apple Inc created and developed the mobile operating system in 1976 and called it iOS.

2. What is ARC?

The abbreviation of ARC is “Automatic Reference Counting”.

3. Is it possible to inherit the structures?

No, there is no way to inherit the structures.

4. Give the definition of Tuples in Swift

There is a Temporary container called Tuples used for multiple values. Tuples is enclosed in parentheses. It has a list of a type that is comma-separated.

5. Define the cloud transfer statements in Swift

The cloud transfer statements are fallthrough, throw, break, return, and continue.

6. What are some most essential Swift features?

Among the core features of Swift, the following can be outlined:

  • Classes in unsafe mode are eliminated.
  • Overflow is checked for Integers and Arrays.
  • Automatic management of Memory is performed.
  • Users apply the Switch function instead of the ‘if’ statement.

7. What is the importance of ‘?’ in Swift?

The question mark ‘?’ at the time of property declaration is applied to make a property optional.

8. How could you define method overloading?

Method overloading is a method that has similar names more than one time but with different arguments.

9. Explain the QoS abbreviation.

QoS is Quality of Service.

10. What is the purpose of QoS?

When we use QoS in iOS, we can dispatch queues and prioritize them, as well as POSIX threads, and thread objects. iOS apps will give a quick response if the user assigns the task priority wise.

11. What is DeadLock?

A deadlock is a situation where two different programs depend on one another for completion (either because both are using).

12. What is Cocoa?

Cocoa provides Foundation and AppKit frameworks for developing apps that run on Mac OS X.

13. How would you explain Cocoa Touch?

Cocoa Touch provides Foundation and UI framework for developing apps that run on iPad, iPhone, and iPod Touch.

14. What are the various property types?

Atomic and non-atomic, assign, strong, weak, retain, and copy compose the various property types.

15. What are the available design patterns of iOS?

The available design patterns of iOS are Façade, Command, Delegate, Model View Controller, Temple method, Observer, and Singleton.

16. What methods are used to pass the data between view controllers?

  • Setting variable directly (Forward)
  • Delegate (Backward)
  • Segue, in prepareForSegue method (Forward)

17. What are the different types of dispatch queues?

  • Main
  • Concurrent
  • Serial

18. What is KVO and why is it important?

KVO means Key-Value Observing. It is used for detecting modifications to a value or property.

19. How is app thinning used?

The concept of app thinning is applied to reduce the app size at the time of downloading.

20. List the different levels of application.

  • Background
  • Active
  • Inactive
  • Suspended
  • Not running

21. What is Delegate in iOS?

In iOS, Delegate is used to generate the relationship between the objects. It serves with one-to-one communication.

22. How would you explain Notification in iOS?

Notification is one-to-many communication. It is used when an object needs to notify other objects of an event.

23. How can you comment on the accountability of URLSession?

URLSession can be used to send and receive HTTP requests.

24. What are the three types of URLSession tasks?

  • URLSessionDownloadTask
  • URLSessionUploadTask
  • URLSessionDataTask

25. What is JSON?

JSON is JavaScript Object Notation. This is a trivial, text-based, and simple method of exchanging and storing data.

26. What is MVC?

MVC stands for Models, Views, and Controller.

27. List three methods to reduce the app size.

  • Bitcode
  • App Slicing
  • On-Demand Resource

28. How can you explain Bundle ID in iOS?

Bundle ID is a unique string that is helpful in identifying the application to the system.

29. What are the certificate types essential for developing and issuing apps?

  • Development Certificate
  • Development and Distributing Certificates
  • Distribution Certificates

30. Provide the binaries that are helpful for installing the app on a device?

Two binaries that are helpful for installing the app on a device are .app and .ipa.

31. Why is Swift used over Objective C?

Swift is a safer, readable, and quick platform, and has less legacy and less code. That is why it is used over Objective C.

32. How can you explain TVMLKit?

TVMLKit is a glue between JavaScript, TVML, and native tvOS apps.

33. What is GCD?

Grand Central Dispatch (GCD) is a library that provides object-based and low-level API to run tasks concomitantly when managing threads that is not in the picture.

34. Give the explanation of iBeacon.

iBeacon allows mobile apps to get the signals from beacons in this physical world and act accordingly.

35. When can you use deinit in Swift?

In order to perform a few actions or cleanup prior to object deallocation, we can use deinit in Swift.

36. How would you explain retain in iOS?

Retain in iOS helps to create an orientation from one object to the other and rises the source object retain count.

37. Give an explanation of assign in iOS.

Assign in iOS helps to create an orientation from one object to the other without raising the source object’s retain count.

38. How to define if an app is not in a running state?

The app will not be in a running state if an app is not launched (or when a system terminates the app at the time of running).

39. How to explain that an app is in active state?

When your app is running in the foreground and retrieving events, it is said to be in active state.

40. What is defer?

Defer is the keyword that affords a code block executed in the situation while execution is exiting the present scope.

41. What is lazy in Swift?

An initial value of lazy stored properties is calculated only when the property is called for the first time. Sometimes, lazy properties are very handy to developers.

42. How can you explain the benefits of the Guard statement?

It avoids the pyramid of doom, provides an early exit out of the function using break or using return, and guards statement is another way to safely unwrap optional.

43. What are the methods for achieving concurrency in iOS?

Operation queues, threads, and dispatch queues are the three methods to achieve concurrency in iOS.

44. Can you list various annotations that are available in Objective C?

  • nullable
  • null_unspecified
  • null_resettable
  • nonnull

45. What are the key features of iOS 12?

  • Natural Language
  • Siri Shortcuts
  • Health Records
  • CarPlay
  • ARKit 2

The main idea of any technical interview is to define how much of a language or platform a candidate knows. Not just the breadth of knowledge, but the depth also.

The tech iOS interview simply determines if someone is worthy of moving forward in the process but doesn’t reveal what a person is like as a developer. The best developers may completely fall to pieces in the practical coding interview, but someone who fails during the interview won’t be a good candidate for the position. 

To sum up

Now you know what questions are asked in an Apple interview. Do not be afraid of an iOS interview and make sure you are well-rested for it. During the interview, talk about the company to which you are applying, its products, and its achievements. Keep your interview answers on-topic, well-structured, and brief.

Do you know the answers to any of the iOS interview questions we mentioned above? If we have missed any important questions, feel free to comment to let us know.