Refined Swift Test - 72+ MCQs: Swift Programming Language Quiz: Test Your Swift Skills

1. What are closures in Swift?

A way to represent a sequence of values in Swift

A mechanism for capturing and storing references to variables and constants

A feature for defining custom attributes in Swift

A set of predefined functions in Swift for handling errors

2. What is the purpose of the 'associatedtype' keyword in Swift protocols?

To specify a default implementation

To declare a typealias within a protocol

To enforce a required initializer

To associate a type with a protocol

3. Which Swift keyword is used to indicate the absence of a value?

nil

void

none

empty

4. What is the purpose of Swift's 'Any' and 'AnyObject' types?

To represent any value in Swift

To declare a constant in Swift

To define a new Swift type

Swift does not have 'Any' and 'AnyObject' types

5. How does Swift handle memory management?

Swift relies on manual memory management

Swift uses automatic reference counting (ARC)

Swift requires explicit deallocation

Swift uses garbage collection

6. What is a 'computed property' in Swift?

A property that is calculated using a function

A property that can only be set once

A property with a fixed value

A property that stores computed values

7. In Swift, what is the purpose of the 'defer' statement?

To immediately execute a block of code

To postpone the execution of a block of code until the end of the current scope

To conditionally execute a block of code

To loop over a block of code

8. What is the purpose of the 'return' keyword in a Swift function?

To print a value

To exit the program

To indicate the end of a loop

To send a value back from a function

9. Explain Swift's 'map', 'filter', and 'reduce' functions.

Predefined mathematical functions in Swift

Functions for handling errors in Swift

Functions for working with arrays, providing transformations, filtering, and combining elements

Syntax sugar for defining Swift properties

10. Explain the use of Swift's 'lazy' keyword.

To define variables that cannot be modified

To create computed properties in Swift

To delay the initialization of a property until it is accessed

To restrict access to a Swift property

11. What is the purpose of the 'unowned' keyword in Swift?

To declare a constant

To define an unwrapped optional

To prevent strong reference cycles

To enforce immutability

12. What is the purpose of an optional in Swift?

To handle errors

To define a default value

To represent a value that may or may not be present

To declare a constant value

13. What is the correct way to check if two strings are not equal in Swift?

string1 <> string2

string1 != string2

string1 ~= string2

string1 .notEqual(string2)

14. What is the purpose of Swift's 'extension'?

To add new functionality to an existing class, structure, enumeration, or protocol

To create a new Swift file

To define a block of Swift code to be executed later

To declare a new type in Swift

15. What is the purpose of the Swift 'guard' statement?

To declare a constant in Swift

To create a guardrail in Swift code

To define a Swift function

To enforce early exit in Swift based on a condition

16. Explain Swift's 'associatedtype' in protocols.

A keyword for defining Swift functions in protocols

A mechanism for specifying the type of an associated value in Swift

An alternative syntax for defining Swift properties

A way to declare global constants in Swift

17. What are generics in Swift?

A mechanism for defining custom operators

A feature for writing concurrent code in Swift

A way to write code that can work with any type

A set of predefined mathematical functions in Swift

18. What is the correct way to concatenate two strings in Swift?

string1 + string2

string1 .concat(string2)

concatenate(string1, string2)

string1 .append(string2)

19. What is the purpose of the 'break' statement in a loop?

To exit the program

To skip the next iteration

To end the loop prematurely

To start a new loop

20. Which keyword is used to declare a constant in Swift?

let

var

const

static

21. In Swift, what does the 'lazy' keyword indicate when used before a property?

The property can be accessed from multiple threads

The property is initialized only when first accessed

The property is immutable

The property is marked for deallocation

22. Which Swift data type is used to store decimal numbers?

Int

Double

Float

Decimal

23. Which operator is used for equality comparison in Swift?

24. In Swift, what is a closure?

A block of code that can be passed around and executed

A mechanism to handle errors

A method for code encapsulation

A class that represents an abstract data type

25. Which Swift keyword is used to start a loop?

start

loop

begin

for

26. What is the purpose of the 'extension' keyword in Swift?

To extend the size of a data type

To add new functionality to an existing type

To create a new class

To override a base class method

27. In Swift, how do you access the first element of an array?

array[0]

array.first

firstElement(array)

array.start

28. Explain the concept of protocol-oriented programming in Swift.

A paradigm emphasizing composition through protocols

A method for writing Swift protocols

An approach to writing procedural Swift code

A way to organize Swift classes hierarchically

29. Explain the concept of Swift's 'inout' parameter.

A parameter indicating input in Swift functions

A keyword for defining class inheritance in Swift

A way to pass a value by reference to a function in Swift

Swift does not have an 'inout' parameter

30. What is the purpose of the 'guard' statement in Swift?

To declare a constant

To create a loop

To check for nil and else execute the code

To define a function

31. In Swift, what is a 'closure'?

A function with a fixed set of parameters

A block of code that can be passed around and called

A type of error handling mechanism

A function with optional parameters

32. What is the purpose of the 'enum' keyword in Swift?

To define a class

To represent an enumeration

To create a function

To declare a protocol

33. Which Swift keyword is used to check multiple conditions in an 'if' statement?

and

multiif

else

34. In Swift, how do you create a comment that spans multiple lines?

// This is a comment

# This is a comment

/* This is a comment */

' This is a comment

35. What are the benefits of using Swift Optionals?

Reducing the need for unwrapping

Avoiding runtime crashes due to nil values

Improving code clarity and safety

All of the above

36. What are the benefits of using Swift's 'struct'?

Automatic memory management

Inheritance and polymorphism

Value semantics and performance benefits

Dynamic method dispatch

37. In Swift, how do you declare a custom error type conforming to 'Error' protocol?

class MyError: Error { }

typealias MyError = Error

error MyError: Error { }

protocol MyError: Error { }

38. Which Swift data type is used to store whole numbers?

Double

Int

Float

String

39. Which collection type in Swift is unordered and does not allow duplicate elements?

Array

Set

Dictionary

Tuple

40. How does Swift handle multiple return values from a function?

Through the use of tuples

By using global variables

Swift does not support multiple return values

By defining multiple functions

41. In Swift, what is the purpose of the 'while' loop?

To repeat a block of code a specific number of times

To iterate over elements in an array

To make decisions based on conditions

To create an infinite loop

42. In Swift, how do you handle errors using the 'try', 'catch', and 'throw' keywords?

try { } catch { } throw { }

throw { } try { } catch { }

try { } throw { } catch { }

catch { } try { } throw { }

43. How does Swift handle optionals and unwrapping?

Optionals in Swift are automatically unwrapped

By using the 'try' keyword

Through forced unwrapping using '!'

Swift does not have optionals

44. What is the purpose of Swift's 'defer' statement?

To declare a Swift function

To postpone the execution of a block of code until the end of the current scope

To implement error handling in Swift

To create a global constant in Swift

45. In Swift, what is the purpose of the 'guard' statement?

To unwrap optionals

To check for nil and else execute the code

To force unwrap optionals

To provide a default value for optionals

46. How can you achieve thread safety in Swift?

By using global variables

By defining multiple classes

Through the use of locks and queues

Swift does not support thread safety

47. In Swift, how do you create an empty array of integers?

var myArray: [Int]

array myArray = []

let myArray = [Int]

emptyArray myArray: Int[]

48. What is the correct syntax for declaring a function in Swift?

function myFunction() { }

def myFunction() { }

func myFunction() { }

sub myFunction() { }

49. What is the correct way to create a range of numbers from 1 to 5 in Swift?

1...5

1..<6

range(1, 6)

range(1...5)

50. What is the purpose of the 'map' function in Swift?

To filter elements in an array

To transform each element in an array using a provided closure

To sort elements in an array

To concatenate arrays

Swift MCQ Test 1