Base class and subclass in Swift - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a base class named Vehicle.

Swift

class [1] {
    var speed: Int = 0
}

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ACar

BTransport

CBike

DVehicle

Attempts:

3 left

💡 Hint

Common Mistakes

Using a subclass name like Car instead of the base class name Vehicle.

The base class is named Vehicle. This is the main class from which others can inherit.

2fill in blank

medium

Complete the code to declare a subclass named Car that inherits from Vehicle.

Swift

class Car: [1] {
    var brand: String = ""
}

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AVehicle

BMachine

CBike

DTransport

Attempts:

3 left

💡 Hint

Common Mistakes

Using a wrong class name after the colon that is not the base class.

The subclass Car inherits from the base class Vehicle using a colon :.

3fill in blank

hard

Fix the error in the subclass initializer to call the base class initializer.

Swift

class Vehicle {
    var speed: Int
    init(speed: Int) {
        self.speed = speed
    }
}

class Car: Vehicle {
    var brand: String
    init(brand: String, speed: Int) {
        self.brand = brand
        [1]
    }
}

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Aself.init(speed: speed)

BVehicle.init(speed)

Csuper.init(speed: speed)

Dinit(speed)

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to call the base class initializer without super.

Calling self.init inside the initializer causing recursion.

In Swift, the subclass must call the base class initializer using super.init(...) to properly initialize inherited properties.

4fill in blank

hard

Fill both blanks to override the base class method and add a new method in the subclass.

Swift

class Vehicle {
    func description() -> String {
        return "Vehicle moving at speed 0"
    }
}

class Car: Vehicle {
    override func [1]() -> String {
        return "Car moving at speed 0"
    }
    func [2]() -> String {
        return "This is a car"
    }
}

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Adescription

Binfo

Cdetails

Dsummary

Attempts:

3 left

💡 Hint

Common Mistakes

Using a different name for the overridden method.

Forgetting the override keyword.

The method description is overridden in the subclass using override. The new method info is added to provide extra information.

5fill in blank

hard

Fill all three blanks to create a subclass that overrides a method and calls the base class method inside it.

Swift

class Vehicle {
    func move() -> String {
        return "Vehicle is moving"
    }
}

class Bike: Vehicle {
    override func [1]() -> String {
        let baseMessage = super.[2]()
        return baseMessage + ", Bike is moving fast"
    }
    func [3]() -> String {
        return "Bike details"
    }
}

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

Amove

Cdetails

Dinfo

Attempts:

3 left

💡 Hint

Common Mistakes

Not calling the base class method inside the override.

Using different method names for override.

The method move is overridden and calls the base class move using super.move(). A new method details is added.