Functions as types in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a function type variable that takes two Ints and returns an Int.

Swift

var operation: [1]

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

Afunc(Int, Int) -> Int

BInt -> Int

CInt, Int -> Int

D(Int, Int) -> Int

Attempts:

3 left

💡 Hint

Common Mistakes

Writing function types without parentheses around input parameters.

Using 'func' keyword inside the type declaration.

In Swift, a function type is written as (InputTypes) -> ReturnType. Here, the function takes two Ints and returns an Int, so the correct type is (Int, Int) -> Int.

2fill in blank

medium

Complete the code to assign a function that adds two Ints to the variable 'operation'.

Swift

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

var operation: (Int, Int) -> Int = [1]

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

Aadd(a:b:)

Badd

Cadd()

Dadd(a, b)

Attempts:

3 left

💡 Hint

Common Mistakes

Calling the function with parentheses instead of referencing it.

Omitting parameter labels in the function reference.

In Swift, to assign a function to a variable, you use the function's name with its parameter labels and colon, like 'add(a:b:)'.

3fill in blank

hard

Fix the error in the function type declaration that should accept a String and return a Bool.

Swift

var check: [1]

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

AString -> Bool

B(String) -> Bool

C(String, Bool)

Dfunc(String) -> Bool

Attempts:

3 left

💡 Hint

Common Mistakes

Omitting parentheses around input types.

Including 'func' keyword in the type.

The correct function type syntax uses parentheses around input types and an arrow to the return type, like (String) -> Bool.

4fill in blank

hard

Fill both blanks to create a dictionary that maps String keys to functions taking Int and returning String.

Swift

var handlers: [[1]: [2]] = [:]

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

AString

B(Int) -> String

CInt

DString -> Int

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping key and value types.

Using incorrect function type syntax.

The dictionary keys are Strings, and the values are functions with type (Int) -> String.

5fill in blank

hard

Fill all three blanks to define a function that takes a function as parameter and returns an Int.

Swift

func performOperation(_ op: [1]) -> [2] {
    return op(5, 3)
}

let add: [3] = { $0 + $1 }

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

A(Int, Int) -> Int

BInt

D()->Void

Attempts:

3 left

💡 Hint

Common Mistakes

Using inconsistent types for function parameter and closure.

Wrong return type for performOperation.

The function parameter 'op' is a function type (Int, Int) -> Int, the return type is Int, and 'add' is a closure of type (Int, Int) -> Int.