Adding initializers via extension in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add a new initializer to the struct using an extension.

Swift

struct Rectangle {
    var width: Double
    var height: Double
}

extension Rectangle {
    init(squareSide: Double) {
        self.width = [1]
        self.height = squareSide
    }
}

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

Aheight

Bwidth

CsquareSide

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using uninitialized variables like width or height instead of the parameter.

Setting width or height to zero.

The new initializer sets both width and height to the same value squareSide to create a square.

2fill in blank

medium

Complete the code to add a failable initializer in the extension that returns nil if the side length is negative.

Swift

struct Circle {
    var radius: Double
}

extension Circle {
    init?(diameter: Double) {
        guard diameter >= 0 else { return [1] }
        self.radius = diameter / 2
    }
}

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

Aself

Bnil

Cfalse

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Returning self or false instead of nil.

Not using a guard statement to check the condition.

The failable initializer returns nil if the diameter is negative, indicating failure to create the instance.

3fill in blank

hard

Fix the error in the extension initializer by completing the missing keyword to call the memberwise initializer.

Swift

struct Point {
    var x: Double
    var y: Double
}

extension Point {
    init(value: Double) {
        [1] init(x: value, y: value)
    }
}

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Areturn

Bsuper

Cinit

Dself

Attempts:

3 left

💡 Hint

Common Mistakes

Using super in a struct, which is invalid.

Omitting self and just writing init(...).

In Swift, to call another initializer from an initializer, you use self.init(...).

4fill in blank

hard

Fill both blanks to add an initializer in the extension that creates a rectangle with equal width and height.

Swift

struct Square {
    var width: Double
    var height: Double
}

extension Square {
    init(side: Double) {
        self.[1] = side
        self.[2] = side
    }
}

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

Awidth

Bheight

Cside

Dlength

Attempts:

3 left

💡 Hint

Common Mistakes

Using property names that do not exist like side or length.

Assigning values to the parameter name instead of properties.

The initializer sets both width and height properties to the same side value.

5fill in blank

hard

Fill all three blanks to add an initializer in the extension that creates a color from RGB values between 0 and 255.

Swift

struct Color {
    var red: Double
    var green: Double
    var blue: Double
}

extension Color {
    init(r: Int, g: Int, b: Int) {
        self.red = Double([1]) / 255.0
        self.green = Double([2]) / 255.0
        self.blue = Double([3]) / 255.0
    }
}

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

Ar

Bg

Cb

D255

Attempts:

3 left

💡 Hint

Common Mistakes

Using the number 255 as a value instead of the parameters.

Not converting Int to Double before division.

The initializer converts integer RGB values to Double between 0 and 1 by dividing by 255.