Collections (Array, Dictionary, Set) in iOS Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create an empty array of integers.

iOS Swift

var numbers: [Int] = [1]

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

AArray()

B{}

C()

D[]

Attempts:

3 left

💡 Hint

Common Mistakes

Using curly braces {} which are for dictionaries or closures.

Using parentheses () which are for tuples or function calls.

The correct way to create an empty array is with square brackets [].

2fill in blank

medium

Complete the code to add a new key-value pair to the dictionary.

iOS Swift

var capitals = ["France": "Paris"]
capitals["Japan"] = [1]

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

A"Tokyo"

BTokyo

C'Tokyo'

Dtokyo

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting quotes around the string value.

Using single quotes which are not valid for strings in Swift.

Dictionary values must be strings in quotes. "Tokyo" is the correct string literal.

3fill in blank

hard

Fix the error in the code to create a set of strings.

iOS Swift

let fruits: Set<String> = [1]

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A["apple", "banana", "cherry"]

BSet(["apple", "banana", "cherry"])

C{"apple", "banana", "cherry"}

D("apple", "banana", "cherry")

Attempts:

3 left

💡 Hint

Common Mistakes

Using square brackets alone creates an array, not a set.

Using parentheses or curly braces incorrectly.

To create a set with values, use Set([...]) with an array inside.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that filters keys with values greater than 10.

iOS Swift

let scores = ["Alice": 12, "Bob": 8, "Eve": 15]
let filtered = scores.filter { $0.value [1] [2] }

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

A>

B10

C<

D15

Attempts:

3 left

💡 Hint

Common Mistakes

Using less than < instead of greater than >.

Using the wrong number for comparison.

The filter checks if the value is greater than 10 using > 10.

5fill in blank

hard

Fill all three blanks to create a dictionary from an array filtering words longer than 4 characters.

iOS Swift

let words = ["apple", "dog", "banana", "cat"]
let dict = Dictionary(uniqueKeysWithValues: words.filter { $0.count [1] [2] }.map { [3] in ([3], [3].count) })

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

A>

B4

C$0

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using $0 as the key variable name in the map instead of a named variable.

Using less than < instead of greater than > in the filter.

The filter uses > 4 to select words longer than 4 letters. The map uses 'word' as the key.