Swift Interview Questions || Technical Interview Questions

Swift Interview Questions

Last Updated by Shikha Sharma 11-Oct-19

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Do you know why Apple's product's performance is so fast? It is because of Swift which is a programming language. Swift code is created so that it can make the applications run without any trouble.

Swift is a very powerful language and it is proposed by Apple.

As we are all aware of the technology developing each day, thus, career scope in this field is also emerging at a rapid pace. Also learning swift is not a difficult task.

Swift Interview Questions

However, if you are planning to fetch your job in this field then listed below are the Most frequent top 15 Swift Interview Questions (updated) that will help you to know the interview questions.

1) What is the Swift Programming language?

Swift Programming language is developed by Apple, which is a general-purpose programming language specifically designed for iOS, Linux, iPadOS, macOS, this language is mainly used for the Apple Cocoa, cocoa-touch framework, and objective C language code coded inside the Apple Products.

It is a very powerful and interactive programming language.

2) What are the 3 features of Swift Programming language?

The features of Swift Programming language are

  • Safe and Fast - Swift Programming Language is very safe and fast. It writes the code in a very safe way and it is also considered as the replacement of the C++, C Objective languages
  • Self-contained code - Swift functions are considered as the self obtained code that means it performs a single specific task as per the requirement.
  • Expressive - the Swift syntax is very easy to utilize and it contains the features preferred by the developers. And also swift programming language is persistently evolving.

Some of the additional features in the Swift programming language are

  • The functional pattern for programming
  • Generics
  • Multifarious return Tuples and values
  • Powerful error handling
  • Latest control flow

3) Name some of the programming languages similar to Swift?

Some of the programming languages that are alike to swift are Python, Ruby, and C objective.

For instance, if we are writing code in Swift then there is no need to complete that particular statement using semicolon exactly like the Python.

4) Differentiate between the methods and functions in the Swift Programming language?

Difference between Methods is Functions in Swift are

Methods in SwiftFunctions in Swift
Methods in Swift are also known as the functions and are always associated with each other for a particular kind. The prime parameter name is the default in the Swift method.Swift Functions are considered as the self obtained code that means it performs a single specific task as per the requirement. "fuc" is used while executing any function. 

5) What is the difference between let and var in Swift?

The differences between let and var in Swift are as follows

Let in Swift cannot be converted as it is considered as an immutable variableVar is the opposite of the left in swift. It can be changed thus considered as a mutable variable.
In another programming language C++, we can define it as a constant.In C++, we can use it as auto, and also we can use Var in Swift more flexibility.

6) What do you know about the dictionary in Swift?

Dictionary in Swift allows us to maintain and keep the key-value pairs along with the access to the value. Likewise, other programming languages, it is similar to hash tables.

7) Define an in-out parameter in Swift?

The parameters parsing in Swift are constant, they cannot be changed. Even if we want to change the parameters, we can change it inside the function. These changes can be cast through the real value outside the function.

8) What is an attribute in Swift?

An attribute in Swift is considered as a construct that offers some extra declaration information. It can be shown by using the @ symbol.

For instance @available(<attribute_name>)

9) What are the types of collections available in Swift?

There are mainly three types of collection available in Swift named as Arrays, Dictionaries, and Sets. These are responsible for keeping a collection of values in swift. Incorrect values or types cannot be inserted in the following collection.

These collections are mutable means the value can be converted or modified as per the operation need.

10) What is a protocol in Swift?

A protocol in Swift explains about the blueprint of methods and other requirements that a task or functionality needs.

11) What do you know about Swift delegates?

Swift delegates are the design patterns created in a manner so that one object can be able to transfer messages to another object whenever required at a particular event.

12) When do we use ? (question mark sign) in Swift?

The sign ? is used while the property declaration. It allows the compiler to know whether the property is optional.

13) What is meant by the Guard statement in Swift?

Guard statement in Swift is a small control flow statement that is responsible for moving the program control from a scope under specific circumstances. The guard statement in swift acts similar to the if statement where the statement runs on certain situations.

Thus, majorly the guard statement works whenever the conditions are not fulfilled.

While working with the guard statements, we must conclude the statements with the break, return, or throw at the completion of the guard statement.

14) How we can write multiple line comments in Swift?

We can write multiple line comments by using -slash and an asterisk (/*) and we are supposed to conclude that comment by using an asterisk with a forward slash (*/).

15) What are the characteristics of Switch in Swift?

The various characteristics of the Switch statement in Swift are:

  • Every type of data is supported by Switch, along with its synchronization and quality verification.
  • There is no need to explicitly breaking out the Switch statement as, after the matching of the case in Switch, the program does not check for the remaining statements.
  • Elimination of break statement is also validated as there is no fall through in the switch statement.
  • All the aspects and values of the Variable must be included due to the exhaustive attribute of the Switch statement.


I hope these questions will help you to crack your interview more easily. If you think I have missed out on any main concept of swift in these questions and answers, you can comment below.

I would be happy to receive your queries.

Thank you and all the best..!!


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