@propertyWrapper declaration in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a property wrapper named Wrapper.

Swift

@propertyWrapper
struct Wrapper {
    var wrappedValue: Int

    init([1]: Int) {
        self.wrappedValue = wrappedValue
    }
}

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

AdefaultValue

Bvalue

CinitialValue

DwrappedValue

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'initialValue' or 'value' as the init parameter label causes compilation errors.

The initializer parameter label for a property wrapper must be 'wrappedValue' to match the synthesized initializer call from the compiler.

2fill in blank

medium

Complete the code to declare a property wrapper with a wrappedValue of type String.

Swift

@propertyWrapper
struct Wrapper {
    var [1]: String

    init(wrappedValue: String) {
        self.wrappedValue = wrappedValue
    }
}

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Avalue

Bproperty

CwrappedValue

Dcontent

Attempts:

3 left

💡 Hint

Common Mistakes

Using other property names like 'value' or 'content' will not work.

The property wrapper must have a 'wrappedValue' property to work correctly.

3fill in blank

hard

Fix the error in the property wrapper declaration by completing the code.

Swift

@propertyWrapper
struct Wrapper {
    private var value: Int

    var [1]: Int {
        get { value }
        set { value = newValue }
    }

    init(wrappedValue: Int) {
        self.value = wrappedValue
    }
}

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Avalue

BwrappedValue

Cproperty

Dcontent

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'value' or other names instead of 'wrappedValue' breaks the wrapper.

The computed property exposing the wrapped value must be named 'wrappedValue' for the property wrapper to work.

4fill in blank

hard

Fill both blanks to complete a property wrapper that clamps an Int value between 0 and 100.

Swift

@propertyWrapper
struct Clamped {
    private var value: Int

    var [1]: Int {
        get { value }
        set { value = min(max(newValue, 0), 100) }
    }

    init([2]: Int) {
        self.value = min(max([2], 0), 100)
    }
}

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AwrappedValue

Bvalue

CinitialValue

DdefaultValue

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong property or parameter names breaks the wrapper.

The property wrapper must use 'wrappedValue' for the exposed property and 'wrappedValue' as the init parameter label.

5fill in blank

hard

Fill all three blanks to complete a property wrapper that stores a String and provides a projectedValue as uppercase.

Swift

@propertyWrapper
struct Uppercase {
    private var value: String

    var [1]: String {
        get { value }
        set { value = newValue }
    }

    var [2]: String {
        value.uppercased()
    }

    init([3]: String) {
        self.value = [3]
    }
}

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

AwrappedValue

BprojectedValue

CinitialValue

Dvalue

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up property names or init parameter causes errors.

The property wrapper uses 'wrappedValue' for the main value, 'projectedValue' for the extra value, and 'wrappedValue' as the init parameter label.