Opaque types with some keyword in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a function that returns some View.

Swift

func makeView() -> [1] {
    Text("Hello")
}

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

AView

Bsome View

Cany View

DOpaque View

Attempts:

3 left

💡 Hint

Common Mistakes

Using just the protocol name without 'some' causes errors.

Using 'any' instead of 'some' changes the meaning.

The some keyword declares an opaque return type, meaning the function returns a specific type conforming to View but hides the exact type.

2fill in blank

medium

Complete the code to declare a variable with an opaque type conforming to Equatable.

Swift

var value: [1] = 5

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

Asome Equatable

Bany Equatable

CEquatable

DOpaque Equatable

Attempts:

3 left

💡 Hint

Common Mistakes

Using just the protocol name without 'some' is not allowed for variables.

Using 'any' instead of 'some' changes the meaning to an existential type.

Using some Equatable declares an opaque type that conforms to Equatable, hiding the exact type but guaranteeing conformance.

3fill in blank

hard

Fix the error in the function return type to use opaque types correctly.

Swift

func getNumber() -> [1] {
    return 42
}

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

AInt

Bsome Int

CNumeric

Dsome Numeric

Attempts:

3 left

💡 Hint

Common Mistakes

Returning a concrete type without 'some' when an opaque type is expected.

Using 'some Int' is invalid because Int is a concrete type, not a protocol.

The function should return some Numeric to use an opaque type conforming to the Numeric protocol, hiding the exact type.

4fill in blank

hard

Fill both blanks to create a function returning an opaque type conforming to CustomStringConvertible.

Swift

func describe() -> [1] {
    return [2](value: 10)
}

struct Wrapper: CustomStringConvertible {
    var value: Int
    var description: String { "Value is \(value)" }
}

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

Asome CustomStringConvertible

BWrapper

CCustomStringConvertible

Dsome Wrapper

Attempts:

3 left

💡 Hint

Common Mistakes

Returning the protocol type directly instead of an opaque type.

Returning a type that does not conform to the protocol.

The function returns some CustomStringConvertible to hide the exact type but guarantee protocol conformance. The returned value is a Wrapper instance.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension with opaque types and a condition.

Swift

let filteredLengths = ["apple", "banana", "cherry"].reduce(into: [:]) { dict, word in
    if word.count [1] 5 {
        dict[word] = word.count [2] 2
    }
}

func makeOpaque() -> [3] {
    return filteredLengths
}

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

A>

B*

Csome Collection

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong comparison operators causing logic errors.

Returning a concrete type without 'some' keyword.

The condition checks if the word count is greater than 5. The dictionary value is the word count multiplied by 2. The function returns an opaque type some Collection.