Array creation and type inference in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create an empty array of integers.

Swift

var numbers = [[1]]()

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

ADouble

BString

CInt

DBool

Attempts:

3 left

💡 Hint

Common Mistakes

Using a type that does not match the intended array elements.

Forgetting to specify the type inside the brackets.

The code creates an empty array of integers by specifying Int inside the square brackets.

2fill in blank

medium

Complete the code to create an array with three string elements.

Swift

let fruits = ["Apple", "Banana", [1]]

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

A"Orange"

B"Carrot"

C"Potato"

D"Milk"

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing a non-fruit string.

Forgetting the quotes around the string.

The array contains fruit names as strings. "Orange" fits the list of fruits.

3fill in blank

hard

Fill in the blank so that Swift infers the array type as [Double].

Swift

var values = [1, 2, [1]]

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

A3.5

B"3.5"

C3

Dtrue

Attempts:

3 left

💡 Hint

Common Mistakes

Using a string instead of a number.

Using an integer literal (causes inference to [Int]).

3.5 is a double literal, causing Swift to infer [Double]. "3.5" is a string, 3 is an integer (inferring [Int]), and true is a boolean.

4fill in blank

hard

Fill both blanks to create an array of booleans with two elements.

Swift

let flags: [Bool] = [[1], [2]]

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

Atrue

Bfalse

C"true"

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using strings instead of booleans.

Using numbers instead of booleans.

The array contains boolean values true and false. Strings or numbers are not valid booleans.

5fill in blank

hard

Fill all three blanks to create a dictionary from strings to integers.

Swift

let scores = [[1]: [2], [3]: 90]

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

A"Alice"

B85

C"Bob"

D100

Attempts:

3 left

💡 Hint

Common Mistakes

Using numbers as keys without quotes.

Using strings as values instead of integers.

The dictionary keys are strings like "Alice" and "Bob". The values are integers like 85 and 90.