Associated types in protocols in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an associated type in the protocol.

Swift

protocol Container {
    associatedtype [1]
}

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AElement

BItem

CType

DValue

Attempts:

3 left

💡 Hint

Common Mistakes

Using a reserved keyword as the associated type name.

Forgetting to write 'associatedtype' before the name.

The keyword 'associatedtype' is followed by the name of the associated type, commonly 'Element'.

2fill in blank

medium

Complete the code to specify the associated type in a struct conforming to the protocol.

Swift

struct Stack: Container {
    typealias [1] = Int
    var items = [Int]()
}

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AItem

BType

CElement

DValue

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different name than the protocol's associated type.

Omitting 'typealias' keyword.

To specify the associated type, use 'typealias' followed by the associated type name, which is 'Element'.

3fill in blank

hard

Fix the error in the protocol declaration by completing the associated type constraint.

Swift

protocol Container {
    associatedtype Element: [1]
}

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ACodable

BComparable

CHashable

DEquatable

Attempts:

3 left

💡 Hint

Common Mistakes

Using a protocol that does not support equality comparison.

Omitting the constraint entirely.

The associated type 'Element' is constrained to conform to 'Equatable' to allow equality checks.

4fill in blank

hard

Fill both blanks to complete the generic function using the protocol with associated type.

Swift

func allItemsMatch<C1: Container, C2: Container>(_ someContainer: C1, _ anotherContainer: C2) -> Bool where C1.[1] == C2.[2] {
    // function body
    return false
}

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AElement

BItem

CValue

DType

Attempts:

3 left

💡 Hint

Common Mistakes

Using different associated type names for the two containers.

Using a name not declared as an associated type.

Both containers must have the same associated type 'Element' to compare their items.

5fill in blank

hard

Fill all three blanks to complete the protocol and conforming struct with associated type and method.

Swift

protocol Container {
    associatedtype [1]
    mutating func append(_ item: [2])
    var count: Int { get }
    subscript(i: Int) -> [3] { get }
}

struct IntStack: Container {
    var items = [Int]()
    mutating func append(_ item: Int) {
        items.append(item)
    }
    var count: Int {
        items.count
    }
    subscript(i: Int) -> Int {
        items[i]
    }
}

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

AElement

BItem

CInt

DValue

Attempts:

3 left

💡 Hint

Common Mistakes

Using inconsistent type names between protocol and struct.

Not matching the associated type with method parameters and return types.

The protocol declares an associated type 'Element', and the methods use 'Element' which is 'Int' in the conforming struct.