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IOS Developer Interview Questions and Answers

Here big day comes for you. Either you have to attend a telephonic interview or face to face interview, things to manage makes you little stressful. To share this stress, we have completed the homework for you. You just have to take a quick tour to get sure shot success in your coming interview. These questions will not only help you in brushing up your skills, but makes you ready for your big day.

Let’s start with some of the basic questions that I hope you are already ready for. They might seem obvious, but you would be shocked how many engineers failed miserably at them during the 12 years I have been doing technical interviews.

IOS Developer Interview Questions

IOS Interview Questions and Answers

IOS is a popular operating system compatible with cell phones, tablets, or smart-phones. Here we will discuss on popular interview questions that are divided into three sections further.

These sections are – IOS tester interview questions and answers, IOS interview questions and answers and the last section is IOS developer interview questions and answers. Let us discuss on each of the sections in detail further.

IOS Interview Questions and Answers

Question: 1. Explain the popular styles to test the IOS apps?

Answer: You can test the devices either on Emulator or you can test the apps on devices itself. An emulator is special software that helps you run apps on system successfully. In case, you use devices itself then there are chances of crashing, but these situations can be avoided in case of emulators.

Question: 2. What are the advantages of using emulators to test IOS apps instead of real devices?


  • You can enjoy the real user experience without damaging real devices
  • Easy installation, Easy to use and really faster as compared to real devices

Question: 3. Is there any disadvantage of emulators?

Answer: Obviously, like any other devices, emulator also has certain pros and cons. Here, you will get a sure shot idea on emulators when to avoid them.

  • If you face memory leaks, or any other memory related issues, then emulators should be avoided.
  • The emulator cannot detect any network or internet related issues.

Question: 4. What are the important facts to consider when you test IOS applications?


  • You need to make sure all test cases are executed on emulator and real device both.
  • If you face memory leaks, or any other memory related issues, then emulators should be avoided.
  • You can detect any network or internet related issues with real devices only.
  • You should check application on the different version of the IOS operating system.
  • You are free to decide on automation tool based on the complexity of a program and so on.

Question: 5. What are the important facts to consider when you test IOS applications on real devices?

Answer: You should check first functional settings and configuration settings of the app. The other things

Read: Android Developer Roles And Responsibilities: You Need To Know

Question: 6. Is it possible to test different size of the screen on devices?

Answer: Yes, you can check the size of the screen on devices with an emulator.

Question: 7. What should be the extension of IOS files while testing different apps?

Answer: The extension should be .ipa while testing different apps either on emulators or real devices.

Question: 8. What is the full form of .ipa and adb in IOS development?

Answer: In IOS development “ipa” stands for IOS app store package and “adb” stands for Android debug bridge.

Question: 9. Name few mobile app testing tools that you have used during your work experience?

Answer: The answer to the question depends on your work experience. Here, we have given the name of few mobile apps that are frequently used by IOS developers. These tools are Android, iPhone, Android Lint, Find bugs, Xcode, and Clang static analyzer etc.

Question: 10. Name the popular APIS that you should focus while testing apps for battery efficiency?

Answer: There are three popular APIs to check the battery efficiency for apps. The name of the APIs is Location Tracking, Region Monitoring, and Visit events. Location tracking API will notify you about a location change at every 500 meters. The Region Monitoring API will notify you about region within a radius of 100 meters or more. Visit events API will notify about places when you enter or exit from a particular location.

IOS Developer Interview Questions and Answers

Question: 11. What do you mean by category and how to use category in your favor?

Answer: A Category is an intelligent idea to add methods in class without extending it. The objective of the category is to add a large collection of methods that are related to each other.

Question: 12. How can you define a protocol for IOS programming and when should you use it?

Answer: The protocol is similar to Java interface defining a list of necessary methods that need to be implemented by a class. The protocol can be implemented by any of the classes or methods without knowing its type.

Question: 13. What are the best security practices to be focused on during IOS programming?


  • Developers should try to establish communication with remote servers only over HTTPs and SSL.
  • As a professional developer, you should know about how to prevent man-in-middle attacks on public attacks.
  • You have to make sure that sensitive data is highly secure and protected by a method overwriting process.
  • Further, don’t forget to check that all data validations have been submitted running on server side.

Question: 14. How will you differentiate synchronous and asynchronous tasks?

Answer: Synchronous calls wait until the task has completed while asynchronous calls complete task in the background and it notifies as soon as you completed.

Read: Android Developer Learning Path

Question: 15. Have you heard about B-trees in IOS development?

Answer: B-tress provides hierarchal storage for key values with excellent characteristics and performance. In case of B-trees, each node contains some values of its own elements that are further connected to its children.

Question: 16. How can you define Enum?

Answer: Enum is a special data type stores group of related values under one umbrella only.

Question: 17. What do you mean by bounding box in IOS programming?

Answer: The bounding box is a popular geometry term refers to the smallest within a given set of points.

Question: 18. What is the role of property @synthesize in IOS?

Answer: The property @synthesize is used to create getter and setter methods for your program. This is easy to work with pre-defined properties once you are sure about their significance and the usage.

Question: 19. How will you differentiate the properties read-only, copy, strong, and weak?


  • “Read-only” command is used to set the initial values and it cannot be changed.
  • “Copy” command is used to copy the value of the objects that can be used somewhere else.
  • “Strong” command will increase the count for the reference by one and its value will be maintained throughout the life of an object.
  • “Weak” command also points one object, but it does not increase its reference count by one.

Question: 20. How will you define the meaning of Code Coverage?Can you set up Live rendering option for IOS app to get the regular live updates?

Answer: For this purpose, you should use @IBDesignable interface to check regular updates on your application. This has become an important functionality today demanded by most of the top organizations.

If you wanted to measure the value of unit tests that it can be done with the concept of Code Coverage.

IOS Developer Questions and Answers For Experienced Candidates

Question: 21. How will you differentiate bounds and frames?

Answer: There is only a minor difference between these two elements. Bounds are limited to their own coordinate system while a frame is related to super view it is contained within.

Question: 22. How will you explain responder chain in IOS?

Answer: Responder Chain is a hierarchy of objects that quickly responds to the events received.

Read: Top 30 Android Interview Questions and Answers

Question: 23. What do you mean by Regular Expressions in IOS?

Answer: Regular expressions are the special type of string patterns that explain you how to look through the particular string.

Question: 24. Explain the behaviour of the operator overloading method?

Answer: Operator overloading allows us to change the behavior of existing methods and behavior accordingly as required for a particular program.

Question: 25. How will you define ABI?

Answer: ABI plays a significant role when it comes to external libraries. This is a special program built to work with particular library and external libraries that is updated later. You don’t have to change the source code if you know how to use ABI for your application.

Question: 26. Explain the importance of design patterns for IOS apps?

Answer: Design patterns are special templates that are designed based on application usage and requirements. The important part is that template code can be reused every time you work with the new application. Design patterns can be majorly defined into two categories – structural, creational, and behavioral.

Question: 27. What do you mean by Singleton Design patterns?

Answer: The Singleton design pattern makes sure that there only a single instance exists for given class and it is necessary to give global access to that particular instance. For the first time, you may experience lazy loading during the creation of single instances.

Question: 28. How will you explain Façade design pattern as a professional IOS developer?

Answer: The Façade design patterns are especially discovered for complex apps where you have to work with unique API only.

Question: 29. What do you mean by Decorator design patterns?

Answer: The Decorator design patterns add special responsibilities and behavior to the objects without making any changes to the source code. They can be used as an alternative to sub-class where it is possible to modify class when wrapped to another object.

Question: 30. Can you please explain about Realm benefits?

Answer: This is an open source database framework that you can implement from scratch. This is highly convenient and fast to use.

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