Property wrappers with configuration 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(wrappedValue: Int) {
        self.[1] = wrappedValue
    }
}

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AwrappedValue

Bvalue

Cproperty

Dwrapper

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different property name than wrappedValue.

Forgetting to assign the wrappedValue in the initializer.

The property wrapper must store the value in a property named wrappedValue.

2fill in blank

medium

Complete the code to add a configuration parameter to the property wrapper.

Swift

@propertyWrapper
struct Wrapper {
    var wrappedValue: Int
    var multiplier: Int
    init(wrappedValue: Int, [1]: Int) {
        self.multiplier = multiplier
        self.wrappedValue = wrappedValue * multiplier
    }
}

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Aconfig

Bfactor

Cvalue

Dmultiplier

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different parameter name than the property name.

Not passing the configuration parameter in the initializer.

The parameter name must match the property name multiplier to configure the wrapper.

3fill in blank

hard

Fix the error in the property wrapper usage with configuration.

Swift

struct Example {
    @Wrapper([1]: 3) var number: Int = 5
}

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Amultiplier

Bfactor

Cvalue

Dconfig

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong argument label that does not match the property wrapper initializer.

Omitting the argument label.

The property wrapper expects a parameter named multiplier, so use multiplier: 3.

4fill in blank

hard

Fill both blanks to complete the property wrapper that doubles the value if enabled.

Swift

@propertyWrapper
struct DoubleIfEnabled {
    var wrappedValue: Int
    var enabled: Bool
    init(wrappedValue: Int, [1]: Bool) {
        self.enabled = enabled
        self.wrappedValue = enabled ? wrappedValue [2] 2 : wrappedValue
    }
}

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Aenabled

B*

C+

D-

Attempts:

3 left

💡 Hint

Common Mistakes

Using the wrong operator like + or - instead of *.

Using a different parameter name than enabled.

The parameter is named enabled and the value is doubled using the * operator.

5fill in blank

hard

Fill all three blanks to create a property wrapper that clamps a value between min and max.

Swift

@propertyWrapper
struct Clamped {
    var wrappedValue: Int
    var min: Int
    var max: Int
    init(wrappedValue: Int, [1]: Int, [2]: Int) {
        self.min = min
        self.max = max
        self.wrappedValue = max(min, min(wrappedValue, [3]))
    }
}

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Amin

Bmax

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up min and max parameter names.

Using min instead of max in the clamping expression.

The parameters are min and max; the wrappedValue is clamped using max(min, min(wrappedValue, max)).