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Swift Interview Questions

Author Lali Sharma
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Swift is a programming language suitable for general-purpose programming and is also a language used for multi-paradigm, and Apple developed it in the year 2014. As for the interview point of view, it is essential when appearing for a job or title related to apple or ios services. 

swift interview questions

Swift is code-safe and runs even on lightweight software. Writing code in Swift is always a fantastic experience for programmers as it is very interactive and simple to understand; the syntax is small and concise but still able to provide fantastic results.

Click on the following link to read further: Java OOPs Interview Questions and Operating System Interview Questions

Swift Interview Questions

Let’s discuss swift interview questions in three parts: easy, medium, and hard.

Easy Swift Interview Questions

1. Why is swift preferred over objective -c? 

The reason for using swift more than objective- c is that swift and objective are object-oriented programming languages. Swift supports tuples, but objective- c does not support tuples.

2 . What symbol is used for property declaration in swift?

The “?” character is used for property declaration in swift, and the “ ? “ is used to tell the compiler that the property is optional or holds any value or not .it stores either value or nil. 

 var optionalname : string? = "Karan"  
   if optional name!= nil {  
    print("the name is \(optional name!)")  }  

3. What do responder chain and regular expression mean in swift? 

A responder chain is a responder chain that responds to the event through

a hierarchical way of objects. A regular expression is a particular string pattern that shows how to search via string.

4. What are the merits of using swift?

The advantages of using the swift language are:

  • User-friendly and easy to read and understand 
  • Low maintenance is easy to maintain and has less maintenance cost.
  • It supports the optional type.
  • Swift is faster and has a unified memory pattern. 

5. How to define variables and constants in swift?

The variables and constants are declared using the “let” keyword and the “var” keyword for variables. 


 var switflan = “this is swift language “
 let num1 = 2000

6. Mentions the types of literals used in swift language.

 The types of literals in swift are:

  • binary literals,
  • octal literals,
  • hexadecimal literals, 
  • decimal literals. Seven, 

7. What are the different statements for control transfer in swift? 

The different statements for control transfer in swift are:

  • control 
  • break 
  • fall through
  • return 

8. What is the continue statement used for in swift loop? 

This statement is used to change the sequence. The execution stops the ongoing information and starts it again from the beginning of the upcoming statement iteration via a loop. 

9. Names the different types of collections available in swift.

There are mainly two types of supplies in swift.

  • Array: we can create two types of arrays in swift. These are the single and multiple types.
  • Dictionary: the dictionary is just like the hash table in different programming languages. The key-value pair in a dictionary and access the value by keys. 

Medium Swift Interview Questions   

  1. What is plist in swift? 

Plist is a property list dictionary made from key-value teams and stores the data in the project file system, i.e., info. plist. 

2. What do you mean by type inference in swift? 

The swift-type inference is the ability to deduce the expression automatically at the time of compilation. 

3. Explain protocols in swift. 

Protocols in swift are like blueprints of the methods used by a class for a particular task 


protocol home {
       func room()
       func hall()
class kitchen: home{
      var making food = false
      func room(){
        sleeping = true

4. Why is mutability used in swift?

In the swift programming language, the variables are mutable. On the other hand, the constants are immutable. Thus mutability can be considered a factor that can differ a variable from a constant in swift. 

5. Define dynamic dispatch used in swift. 

The term dynamic dispatch is essential from the object-oriented perspective and is the core primary mechanism that can perform runtime polymorphism. 

6. What access control is in swift? 

Access control is used or restricts the parts of the code from the code in other source files and modules. This hides the code implementation from the source code.

7. Define open access control and public access control.

  • open-access control: in the open-access control, the class and the class members can be overridden both within and outside of the module.
  • public access control: the public access controls class and class members can only be overridden within the defined module. 

8. What is the use of extensions in swift?

An extension in swift adds new functionality to the predefined class, structure, or protocol type. It also holds the ability to extend the kind for which there is no requirement for source code. The extensions in swift are very similar to that in objective- c  only difference is that they do not have names.

9. What is a type alias in swift? 

The type alias introduces a named alias of an existing class into the program. The type alias is declared using the “typealias” keyword. 

typealias my_list = dictionary<string, int > 

10. What is forced unwrapping in swift?

When a variable is defined as optional, the unwrap is used in swift to get the value from the optional variable. 

Hard Swift Interview Questions 

  1. What is optional binding? 

The optional binding is used to find whether the optional variable contains the value. Or any discount is available, either temporary or permanent.

if let home = someoptional {
   home decode

2. What are identical operators?

In swift, there are three or more identical operators mentioned below 

  1. === ( or ==!) 
  • It is used for checking the value for both points to the same memory address 
  • It is used for comparison of the reference type. 
  • it is used similar to == used in objective -c. 

2. ==(or !=) 

  • It is used to check whether the values are the same and to compare the value type.
  • It is similar to is equal: in objective-c

3. From the following code, answer the following question.

var arr1 = [ a,b,c,d,e,f]
var arr2 = arr1 
var len = arr1.count


arr1 = [a,b,c,d,e,f]
arr2 = [a,b,c,d,e,f,g]

4. What do you understand about the higher-order functions?

The higher-order function takes one or more functions as arguments or returns a function. Higher-order functions are also used to enhance 

readability and reduce the length of the code. 

5. Differences between array and nsarray?

typevalue typereference type
contentsame type of dataall types of data

6. What is the function of init()?

The inti() in swift is used to initialize a structure or class; it's a property inside the initial value. This method allows leaving stored properties to be avoided in the intermediate state. This function also checks the line or symbol causing an error in the execution process of the code.  

7. Mention the key difference between structure and classes.

data typereference typevalue type
manually deinitializedyesno
inherit from another classyesno

8. Why swift uses immutability? 

Immutability is one of the important and core for swift coding. Immutability is important because it ensures that the data cannot be changed and creates consistent variable usage and optimized data storage. All the unnecessary errors and wasted time is also avoided using immutability.


This article covered the topic of Swift Interview Questions. In this, we have discussed critical questions generally asked in the interview related to Swift Interview Questions from basic to advanced. It was all about the report. I hope you all found these swift interview questions interesting and helpful.

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