How Swift compiles to native code - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a simple Swift function.

Swift

func greet() -> String {
    return [1]
}

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

Areturn Hello

BHello, world!

C"Hello, world!"

Dprint("Hello, world!")

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to put quotes around the string.

Trying to return a print statement.

The function must return a string literal enclosed in quotes.

2fill in blank

medium

Complete the code to declare a variable with type Int.

Swift

var number: [1] = 10

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

AInt

BDouble

CString

DBool

Attempts:

3 left

💡 Hint

Common Mistakes

Using String or Double instead of Int.

Omitting the type annotation.

The variable 'number' is declared as an integer type, so use Int.

3fill in blank

hard

Fix the error in the function declaration to compile correctly.

Swift

func add(a: Int, b: Int) -> [1] {
    return a + b
}

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

AInt

BString

CBool

DVoid

Attempts:

3 left

💡 Hint

Common Mistakes

Using String or Bool as return type incorrectly.

Using Void when the function returns a value.

The function adds two integers and returns an integer, so the return type must be Int.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps numbers to their squares for numbers greater than 3.

Swift

let squares = Dictionary(uniqueKeysWithValues: (4...7).map { [1] in let [2] = [1] * [1]; ([1], [2]) })

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

Anum

Bval

Cx

Dy

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names inconsistently.

Not matching the closure parameters with the map function.

We use 'num' and 'val' as variable names in the closure to map numbers to their squares.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps uppercase letters to their ASCII values for letters 'a' to 'd'.

Swift

let asciiDict = Dictionary(uniqueKeysWithValues: ("a"..."d").map { [1] in let [2] = [1].uppercased(); ([1].uppercased(), Int([3].unicodeScalars.first!.value)) })

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

Aletter

Bchar

Attempts:

3 left

💡 Hint

Common Mistakes

Using inconsistent variable names.

Not converting the character to uppercase for the key.

The closure uses 'letter' and 'char' as parameters; the uppercase letter is the key, and its ASCII value is the value.