Swift Arrays and Collections Quiz

This quiz covers the fundamentals of working with collections in Swift, specifically arrays and dictionaries. These questions cover a range of topics including the initialization and manipulation of arrays and dictionaries, their properties and methods, and specific usage scenarios like mutable vs immutable collections, accessing and modifying data, and iterating through collections.

Which of the following data types can be used as keys in a Swift dictionary?

Double, String, Enum

Any, AnyObject, Array

String, Int, Array, Bool

String, Int, Double, Bool

None

Which property of a collection returns the number of elements it contains?

count

total

length

size

None

How do you iterate over the key-value pairs of a dictionary in Swift?

Using a while loop

Using a for-in loop with (key, value)

Using map()

Using reduce()

None

What is the output of the following code?

var colorDict = [1: "red", 2: "green"]
colorDict[3] = "blue" 
print(colorDict)

[1: "red", 2: "green"]

[1: "red", 2: "green", 3: "blue"]

nil

[3: "blue"]

None

Which syntax correctly declares a dictionary with default values?

let dict = [key: defaultValue]

let dict = Dictionary(key: defaultValue)

let dict = Dictionary(uniqueKeysWithValues: [(key, value)])

let dict = [key: value] ?? defaultValue

None

What happens when you assign nil to a dictionary key?

The dictionary is cleared.

The key is ignored.

The key is removed from the dictionary.

The key's value becomes null.

None

How do you remove a key-value pair from a dictionary in Swift?

dictionary.removeLast()

dictionary.removeValue(forKey: key)

dictionary.removeAt(key)

dictionary.delete(key)

None

What does the following code do?

bookDict["200-532874"] = "War and Peace"

It removes the key "200-532874" from the dictionary.

It updates the value associated with the key "200-532874".

It adds a new key-value pair to the dictionary.

It deletes all key-value pairs in the dictionary.

None

What will happen if you try to access a key in a dictionary that does not exist?

The compiler throws an error.

The program crashes.

You get nil or the default value if provided.

The value is automatically inserted.

None

10.

Which of the following is true about collections in Swift?

Collections in Swift do not exist.

Collections can only be mutable.

Collections can be either mutable or immutable.

Collections can only be immutable.

None

11.

How can you create a dictionary from two arrays in Swift?

Using forEach() method

Using zip() function

Using map() method

Using append() method

None

12.

What is the purpose of the randomElement() method in Swift arrays?

To randomly select and return an element from the array.

To add a random element to the array.

To access the first element in the array.

To shuffle the elements of the array.

None

13.

What is the result of the following code?

let macArray = ["MacBook Pro", "Mac mini", "MacBook Air", "Mac Studio"] 
let shuffledMacs = macArray.shuffled()

shuffledMacs contains only the first element.

shuffledMacs contains the same elements in random order.

shuffledMacs is an empty array.

shuffledMacs is a copy of treeArray.

None

14.

Which syntax correctly initializes an empty dictionary in Swift?

var dictionary = [:]

var dictionary = [Any: Any]()

var dictionary = [keyType: valueType]()

var dictionary = Dictionary()

None

15.

How can you insert an item at a specific index in an array?

array.push(item, at: index)

array.add(item, at: index)

array.put(item, at: index)

array.insert(item, at: index)

None

16.

What will be printed after executing the following code?

let macArray = ["MacBook Pro", "Mac Mini", "MacBook Air", "Mac Studio"] 
macArray[1] = "Mac Pro" 
print(macArray[1])

"Mac Pro"

nil

"Mac Mini"

"MacBook Pro"

None

17.

Which method can be used to remove the last element of an array?

deleteLast()

removeLast()

remove()

pop()

None

18.

How do you check if an array is empty in Swift?

array == []

array.isEmpty

array.isEmpty()

array.size == 0

None

19.

What is the correct way to append an item to an array in Swift?

array.add(item)

array += item

array.append(item)

array.insert(item)

None

20.

Which method can be used to randomly shuffle the contents of an array?

random()

shuffle()

shuffled()

mix()

None

21.

Which syntax is used to initialize an empty array in Swift?

var array = Array()

var array = new Array()

var array = []

var array = [type]()

None

22.

How can you make a collection immutable in Swift?

Use the `let` keyword inside the collection.

Assign it to a variable.

Use the `immutable` keyword.

Assign it to a constant.

None

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