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 Technical swift interview Question and Answer for iOS developer: Part 3

iOS interview Questions swift and Answer for experience and fresher candidate

iOS interview questions swift for experience student for preparation of job interview

1 .What is ARC (Automatic Reference Count ) ?

ARC ( Automatic Reference Count ) is the used to manage and track the memory in iOS Application . It Automatically manage the application memory and release the class memory when it is no longer needed.

2.What is difference between Foundation and Core Foundation?

Core Foundation

is the C-level API, which provides CFString, CFDictionary and the like.


is Objective-C, which provides NSString, NSDictionary, etc.

3.How many states are there in iOS life cycle?

  • Not running
  • Active
  • Inactive
  • Suspended
  • Background

4. In Which thread does Api gets called?

 In background Thread Api services gets call

Ex URLSession.shared.dataTask

5. What is singleton class in swift ?

SingleTon class is the  object  which provide single point of access to the function of the class

Class Common  { 
static let shared = Common()
 private init()      
func sum()-> Int { 
     return 10 + 20   

accessing the singleton

let Sum = Common.shared.sum() 
print (Sum)

output Sum = 30

6.What are the difference between Cocoa and Cocoa Touch ?

  • Cocoa is the combination of Foundation and Appkit
  • Cocoa touch is the combination of Foundation and UIKit
  • Cocoa is basically related to MAC OS
  • Cocoa touch is related to all the Devices of the Apple


  • Cocoa: All the classes used in Cocoa have the NS prefix Ex: NSTextField
  • Cocoa Touch: classes used in Cocoa have the UI prefix Ex: UITextField

7. What is the use of reuseIdentifier in swift ?

ReuseIdentifier is used  to group the cell of the UItableview.

8. What are the Different types of DisPatchQueue?

Main , concurrency and Serial

9. What is KV0 ?

 KVO(Key value observer) is used to detect the changes in property or value.

10 . What is Lazy Property in swift ?

A lazy stored property is a property whose initial value is not calculated until the first time it is used. You indicate a lazy stored property by writing the lazy modifier before its declaration. iOS interview Question and Answer : Part 3 for more iOS interview Questions swift and Answer