300+ TOP SWIFT Interview Questions and Answers

SWIFT Interview Questions for freshers experienced :-

1. What is Swift Programming Language ?
Swift is a programming language and system for creating applications for iOS and OS X. It is an innovative programming language for Cocoa and Cocoa Touch.

2. What are the features of Swift Programming?
Features of Swift Programming are:

1. It eliminates all the classes of unsafe code
2. Variables are initialized before use
3. Integers are checked for overflow
4. Arrays are checked for overflow
5. Memory management is automatic
6. swift has “switch” function Instead of “If” statement

3. What are the types of collection available in Swift?
There are two types of collections available in Swift are:

Array (Array of a single type or an array with multiple types)
Dictionary(Similar to a Hash table as in other programming language)

4. List out what are the control transfer statements used in Swift?
Control transfer statements used in Swift are:

• Break
• Return
• Continue
• Fallthrough

5. How to define Constants and Variables in Swift language?
Before Constants and Variables are used they must be declared.

Constants declared with “let” keyword and Variables are declared with “var” keyword.

6. What are the types of access control in Swift language?
There are three types of access control in Swift language are:

• Public
• Internal
• Private

7. What are the characteristics of Switch in Swift?
Characteristics of Switch in Swift are:

• Switch statement must be exhaustive
• There is no fallthrough in switch statements
• Supports any kind of data
• Supports synchronization and also check for equality

8. What are the types of Integer Literals available in Swift language?
There are four types Integer Literals in Swift are:

Decimal
Example: decimal Integer = 17

Binary (Begin with 0b)
Example: binary Integer=0b10001

Octal (Begin with 0o)
Example: octal Integer = 0o21

Hexadecimal (Begin with 0x)
Example: hexadecimal Integer=0x11

9. What are the types of Operators available in Swift language?
Types of Operators in Swift are :

• Misc Operators
• Range Operators
• Logical Operators
• Bitwise Operators
• Assignment Operators
• Arithmetic Operators
• Comparison Operators

10. What is ARC in Swift?
ARC is stands for Automatic reference counting.

It is used for Memory Management and provides information about the relationships between our code instances.

It is also is used to initialize and deinitialize the system resources.

11. Write a basic program in Swift to print “Swift Expert” for OS X playground?
Example:

import Cocoa

var myString = “Swift Expert”

println(myString)

Output:

Swift Expert

12. Write a basic program in Swift to print “iOS Playground” for iOS playground?
Example:

import UIKit

var myString = “iOS Playground”

println(myString)

Output:

iOS Playground

13. What are the types of decision making statements available in Swift language?
Types of decision making statements in Swift Language are:

if statement:
It consists of a Boolean expression followed by one or more statements.

if…else statement
if…else if…else Statement

nested if statements:
Here we can use one if or else if statement inside another if or else if statement.

switch statement:
It is used to test a variable for equality against a list of values.

14. What is Initializers in Swift language?
Initializers: It is used to add new initializers to an existing type by extensions.

Here, extensions supports only init() and deinit() is not supported by the extensions.

15. What are the Features of “Objective-C” language?
Features of “Objective-C” language :

• Variables are declared as NSString and constant as int
• Here, the code ends with semi-colon
• Here we need to choose between NSMutableString and NSString for string to be modified
• addObject() method of NSMutable array is used to append a new item to an array

16. Who is the developer of Swift programming language?
Chris Lattner is the developer of Swift programming language.

17. What is import in Swift?
Import: We can use the import statement to import any Objective-C framework, libraries and APIs directly into your Swift program.

18. What are the types of built-in data types available in Swift?
The types of built-in data types available in Swift are:

• Int or UInt
• Float
• Double
• Bool
• String
• Character
• Optional

19. What is the syntax to declare the typealias in Swift?
The syntax to declare the typealias is:

typealias newname = type

20. What is the syntax to declare variables in Swift?
The syntax to declare variables in Swift:

var variableName = <initial value>

21. What are the two values of optional in Swift programming language?
The two values of optional are:

1. None
2. Some(T)

22. What is the syntax to declare optional Integer in Swift?
The syntax to declare optional Integer is:

var perhapsInt: Int?

23. What is the syntax to declare Constants in Swift?
The syntax to declare Constants is:

let constantName = <initial value>

24. What is String literal in Swift?
String literal: It is a sequence of characters surrounded by double quotes. It cannot contain an unescaped double quote (“), an unescaped backslash (\), a line feed, or a carriage return.

25. What is the use of fallthrough statement in Swift?
fallthrough statement: This statement is used to simulate the behavior of swift switch to C-style switch.

26. Which literal is used to create an empty string in Swift?
Empty String literal is used to create an empty string in Swift.

27. Which Boolean property is used to check whether a string is empty or not?
isEmpty Boolean property is used to check whether a string is empty or not.

28. What is the use of hasPrefix(prefix: String) function in Swift?
hasPrefix(prefix: String) function: This String function is used to check whether a given parameter string exists as a prefix of the string or not.

29. What is utf8 in Swift?
utf8 is a property of String that is used to return a UTF-8 representation of a string.

30. What is the use of enumerate() function in Swift array?
enumerate() function: This function is used to return the index of an item along with its value.

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