Why collections are value types in Swift - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create an array and add an element.

Swift

var numbers = [1, 2, 3]
numbers.[1](4)

Drag options to blanks, or click blank then click option'

Apush

Badd

CinsertAt

Dappend

Attempts:

3 left

💡 Hint

Common Mistakes

Using methods like 'add' or 'push' which are not valid for Swift arrays.

The append method adds an element to the end of an array in Swift.

2fill in blank

medium

Complete the code to copy an array and modify the copy without changing the original.

Swift

var original = [1, 2, 3]
var copy = original
copy.[1](4)
print(original.count)

Drag options to blanks, or click blank then click option'

AremoveLast

Bappend

Cclear

Dinsert

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'removeLast' or 'clear' which remove elements instead of adding.

Appending to the copy does not change the original array because arrays are value types in Swift.

3fill in blank

hard

Complete the code to add "Cherry" to the fruits array.

Swift

var fruits = ["Apple", "Banana"]
fruits.[1]("Cherry")

Drag options to blanks, or click blank then click option'

Aappend

Badd

Cinsert

Dpush

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to modify a constant array (let) or using invalid methods like 'push'.

To modify an array, it must be declared with var, not let which creates an immutable value. Use append to add an element to the end.

4fill in blank

hard

Fill both blanks to create a dictionary and add a new key-value pair.

Swift

var capitals = [1]<String, String>()
capitals["France"] = [2]

Drag options to blanks, or click blank then click option'

ADictionary

B"Paris"

CArray

D"London"

Attempts:

3 left

💡 Hint

Common Mistakes

Using Array instead of Dictionary for the first blank.

Use Dictionary to create a dictionary and assign the value "Paris" to the key "France".

5fill in blank

hard

Fill all three blanks to create a set, add an element, and check if it contains a value.

Swift

var fruits = [1]<String>()
fruits.[2]("Apple")
let hasApple = fruits.[3]("Apple")

Drag options to blanks, or click blank then click option'

ASet

Binsert

Ccontains

Dappend

Attempts:

3 left

💡 Hint

Common Mistakes

Using append which is for arrays, not sets.

Use Set to create a set, insert to add an element, and contains to check if the set has a value.