Calling super for parent behavior in Swift - Mini Project: Build & Apply

Calling super for parent behavior

📖 Scenario: Imagine you are creating a simple app with different types of vehicles. Each vehicle can start its engine, but some vehicles have extra steps when starting. You will learn how to use super to call the parent class behavior and add extra steps in child classes.

🎯 Goal: You will build a small Swift program with a parent class Vehicle and a child class Car. You will override a method in the child class and call the parent method using super to keep the original behavior and add new behavior.

📋 What You'll Learn

Create a class called Vehicle with a method startEngine() that prints "Engine started".

Create a subclass called Car that inherits from Vehicle.

Override the startEngine() method in Car and call the parent method using super.startEngine().

Add an extra print statement in Car's startEngine() method that prints "Car is ready to go!".

Create an instance of Car and call its startEngine() method to see both messages.

💡 Why This Matters

🌍 Real World

In real apps, many classes inherit from others and override methods to add or change behavior. Using <code>super</code> helps keep the original behavior while extending it.

💼 Career

Understanding inheritance and calling parent methods is essential for Swift developers working on iOS apps, especially when working with UIKit or SwiftUI where subclassing is common.

1

Create the Vehicle class

Create a class called Vehicle with a method startEngine() that prints exactly "Engine started".

Swift

// Create the Vehicle class with startEngine() method
// Your code here

Need a hint?

Use class Vehicle {} and inside it define func startEngine() that prints the message.

2

Create the Car subclass

Create a subclass called Car that inherits from Vehicle.

Swift

class Vehicle {
    func startEngine() {
        print("Engine started")
    }
}

// Create the Car subclass inheriting from Vehicle
// Your code here

Need a hint?

Use class Car: Vehicle {} to create the subclass.

3

Override startEngine() and call super

In the Car class, override the startEngine() method. Inside it, call the parent method using super.startEngine() and then print exactly "Car is ready to go!".

Swift

class Vehicle {
    func startEngine() {
        print("Engine started")
    }
}

class Car: Vehicle {
    // Override startEngine() here
    // Your code here
}

Need a hint?

Use override func startEngine() and inside call super.startEngine() before printing the extra message.

4

Create Car instance and call startEngine()

Create an instance of Car called myCar and call its startEngine() method to print both messages.

Swift

class Vehicle {
    func startEngine() {
        print("Engine started")
    }
}

class Car: Vehicle {
    override func startEngine() {
        super.startEngine()
        print("Car is ready to go!")
    }
}

// Create myCar instance and call startEngine()
// Your code here

Need a hint?

Create let myCar = Car() and then call myCar.startEngine().