Top IOS Interview Questions and Answers

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Are you preparing to break into a career as iOS developer? If yes, ease the stress and brush up on some of the skills you haven’t used in a while – you are all set to go. The demand for iOS developers is expected to shoot through the roof due to adoption of iOS devices.

Let’s take a look at some of the top frequently asked iOS interview questions and answers which will be a great self-test if you are seeking some practice for your IOS interview.

 

Q1. What is ARC?

 

Ans. ARC (Automatic Reference counting) is a compiler level feature that defines the process of managing the lifetime of objects in objective-C.

 

Q2. Define Bundle ID?

 

Ans. Bundle ID is used for both OS X apps and iOS.  It uniquely defines every iOS application. A bundle identifier can recognize any update to your app.

 

Q3. Name some important data types found in objective-C?

 

Ans. There are four data types which are as follows:

  • Bool
  • CGfloat
  • NSintegar
  • NSstring

 

Q4. Define Cocoa/Cocoa touch?

 

Ans. It is used for building software codes to run on iOS for the iPad and iPhone. Cocoa Touch is written in the objective-C language and has a different set of graphical control elements to Cocoa.

 

Q5. What programming languages are used for iOS development?

 

Ans.

  • HTML5
  • .NET
  • C
  • Swift
  • Javascript
  • Objective-C

 

Q6. What are the methods to achieve concurrency?

 

Ans. The methods to achieve concurrency are:

  • Dispatch queues
  • Threads
  • Operation Queues

 

Q7. What is the difference between atomic and nonatomic synthesized properties?

 

Ans. Atomic:

  • Default behavior
  • Not fast
  • Make certain the process is completed entirely by CPU

Nonatomic:

  • Not default behavior
  • Faster
  • Not able to deal with multiple requests at same time

 

Also Read>> Clash of the Titans: Android vs. iOS!

 

Q8. When is an app said to be in not running state?

 

Ans. It is said when it is not launched or gets terminated by system while running.

 

Q9. Explain object?

 

Ans. Objects are mainly the variables that are of class types. It can be a function, method, data structure or a variable.

 

Q10. When would you say that an app is in active state?

 

Ans. An app is said to be in active state when it is accepting events and running in the foreground.

 

Q11. Which framework is used to construct application’s user interface?

 

Ans. UIKIT framework. It renders drawing model, windows, event handling and views.

 

Q12. What is iBeacon?

 

Ans. iBeacon enables mobile apps to listen signals from beacons in the physical world and respond accordingly. It comprises of two parts: a broadcaster and a receiver.

 

 

Q13. What is Method Swizzling?

 

Ans. The process of changing the implementation of an existing domain, Method Swizzling enables you to write that a code that can be executed before or after the original method.

 

Q14. When is category used?

 

Ans. It is used to add a set of related method and to add additional methods in the Cocoa framework.

 

Q15. What is the difference between Viewdidload and Viewdidappear?

 

Ans. Viewdidload:

  • It is called when it is loaded into memory
  • Data can be loaded in Viewdidload if it is fairly static and likely to change

Viewdidappear:

  • It is called when the view is visible and presented on the device
  • You can perform any layout functions or drawing in the UI

 

Q16. What does KVO stands for?

 

Ans. KVO means key value observing which enables a controller to observe changes to a property value.

 

Q17. Which is the latest IOS development platform?

 

Ans. The latest iOS development platform is iOS 9.2 beta 2 Build version: 13C5060d

 

Also Read>> Create Your Own Mobile Application in 5 Simple Steps!

 

Q18. What are two different smart groups in Xcode?

 

Ans. Smart Groups are divided into two parts:

  • Simple expression smart group
  • Simple filter smart group

 

Q19. How can you open the Code Snippet Library in Xcode?

 

Ans. CMD+OTP+Cntrl+2

 

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Twinkle kapoor

Though from a techie background, her interest in writing on plethora of topics has made her today an experienced writer. She has written articles, blogs and web page content for oodles of websites.