iOS Interview Questions and Answers

Last updated on Feb 10, 2022
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iOS Interview Questions

iOS, formerly known as iPhone OS, is a mobile OS created and developed by Apple for its hardware. This operating system powers most of Apple’s devices, including iPhones, iPads, and iPod Touch. iOS is the world’s second most popular mobile OS after Android. The iOS UI is based on direct manipulation by using multi-touch. Apple has been active in including accessibility functions into iOS that even enable users with vision and hearing disabilities to use its products properly. If you have read our IOS interview questions, you can find your next dream job soon.


  • User-friendly
  • Intuitive and fluid responsive
  • Excellent UI that works equally good for all purposes - media entertainment, gaming and business.
  • Less heat generated as compared to Android.
  • Best-in-class security.

Most Frequently Asked iOS Interview Questions

Here in this article, we will be listing frequently asked iOS Interview Questions and Answers with the belief that they will be helpful for you to gain higher marks. Also, to let you know that this article has been written under the guidance of industry professionals and covered all the current competencies.

Q1. What are the CPU architectures supported by iOS devices?
There are CPU designs upheld by IOS gadgets:-

iPhones and Ipads

  • Arm64 is the current 64-bit ARM CPU design, as utilized since the iPhone 5S and later (6, 6S, SE and 7), the iPad Air, Air 2 and Pro, with the A7 and afterward chips.
  • armv7s (a.k.a. swift, not to be confused with the language of a similar name), is utilized in Apple's A6 and A6X chips on iPhone 5, iPhone 5C and iPad 4.
  • armv7, a first variation of the 32-bit ARM CPU, as utilized in the A5 and prior.


  • On tvOS, Elements underpins three structures for gadget sending:
  • arm64 is the current 64-bit ARM CPU design and utilized on Apple TV 4
  • x64_64 (i.e., 64-bit Intel) is utilized in the Simulator


  • On tvOS, Elements underpins three designs for gadget arrangement:
  • Armv7k is a 32-bit variation of standard armv7 and utilized on Apple Watch Series 0, 1 and 2.
  • i386 (i.e., 32-bit Intel) is utilized in the Simulator
Q2. What iOS version onwards ARC can be used?

ARC is an IOS 5 specific feature and using storyboard means that you need to raise minimum supported OS to IOS 5.

Q3. Can we support the same application for iPhone 3GS and iPhone 5, 6, 7? Why not?

We cannot support the same application for iPhone 3GS AND 5, 6, 7 because iPhone 3GS doesn’t support IOS6 or later versions.

Q4. Would I be able to keep in touch with some C++ work in the equivalent .m record? Will it compile? Assuming no, what changes would it be a good idea for me to do to compile it?

The easiest solution is to inform Xcode to compile everything as Objective C++ merely. Set your target on the settings to Compile Sources As to Objective C++ and recompile. After that use C++ or Objective C anywhere you want.

Q5. What are the sorts of iOS binaries you can make utilizing Xcode?

you can create .app, .ipa, .a and .framework.

Q6. Can a static library (.a) contain assets like pictures, sound documents and so on.?

NO, You can’t offer something aside from code with a static library. This is often as a result of .a files measure an accessible archive of object files, with the extra ability beneath Mac/iOS of supporting multiple processor architectures.

Q7. What is the responder chain?

The responder chain is a series of coupled responder objects. It starts with the primary responder and finishes with the app object. If the primary responder cannot handle an occurrence, it forwards the event to consecutive responder within the responder chain.

Q8. Tell me the hierarchy of UIButton.

NSObject -> UIResponder ->UIView -> UiControl ->UIButton.

Q9. Why UIControl is provided if we can create custom UIView?

You can additionally produce a custom read to encapsulate the visual appearance and behavior of your own reusable element. For instance, in a very news reading application, we would desire a standard part to show pictures with a caption employing a consistent style on each the home page view controller similarly individual story view controller.

Q10. App Life Cycle.

An app in iOS goes through completely different states as it runs. These shows the states of the appliance life cycle. Below are the states of the associate app.

  • Not running

The application has not been running or was launched however was terminated by the system.

  • Inactive

The app is running within the foreground; however, it is presently not receiving events. (It is also death penalty alternative code though) the associate app typically stays during this state because it transitions to a distinct state.

  • Active

The app is running within the foreground and is receiving events. This is often the conventional mode for foreground apps.

  • Background

The app is within the context and executing code. Most apps enter this state shortly on their way to being suspended. However, an associate app that requests additional execution time might stay during this state for an amount of your time. Additionally, an app being launched directly into the background enters this state rather than the inactive state. For info concerning the way to execute code whereas within the environment, see Background Execution.

  • Suspended

The app is within the background; however, executing code isn’t. The system moves apps to the current state mechanically and doesn't send word them before doing this. Whereas suspended, the associate app remains in memory however doesn't execute any code.

Development History

iOS was unveiled in 2007 by Apple for its iPhone. Since then versions have been released annually.

Latest Version: The latest version is iOS 12, which was released in September 2018. Memorize this information for IOS interview questions and answers.

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