Overriding methods and properties in Swift - Mini Project: Build & Apply

Overriding methods and properties

📖 Scenario: You are creating a simple app to manage different types of vehicles. Each vehicle has a basic way to describe itself, but some vehicles have special descriptions.

🎯 Goal: Build a Swift program that defines a base class Vehicle with a method and a property, then create a subclass Car that overrides the method and property to provide a custom description.

📋 What You'll Learn

Create a class called Vehicle with a method description() that returns a String.

Add a property type in Vehicle that returns a String.

Create a subclass called Car that inherits from Vehicle.

Override the description() method in Car to return a custom string.

Override the type property in Car to return a different string.

Print the results of calling description() and accessing type on an instance of Car.

💡 Why This Matters

🌍 Real World

Overriding methods and properties is common when you want to create specialized versions of general objects, like different types of vehicles in an app.

💼 Career

Understanding overriding is essential for iOS developers to customize behavior in subclasses and build flexible, reusable code.

1

Create the base class Vehicle

Create a class called Vehicle with a method description() that returns the string "This is a vehicle" and a computed property type that returns the string "Generic Vehicle".

Swift

# Create class Vehicle with method description() and property type
# Your code here

Need a hint?

Use class Vehicle {} to define the class. Inside, add func description() -> String and a computed property var type: String.

2

Create subclass Car and override property

Create a subclass called Car that inherits from Vehicle. Override the computed property type to return the string "Car".

Swift

class Vehicle {
    func description() -> String {
        return "This is a vehicle"
    }
    var type: String {
        return "Generic Vehicle"
    }
}

# Create subclass Car that overrides property type
# Your code here

Need a hint?

Use class Car: Vehicle {} to create the subclass. Use override var type: String to change the property.

3

Override the description() method in Car

In the Car class, override the method description() to return the string "This is a car".

Swift

class Vehicle {
    func description() -> String {
        return "This is a vehicle"
    }
    var type: String {
        return "Generic Vehicle"
    }
}

class Car: Vehicle {
    override var type: String {
        return "Car"
    }
    
    # Override description() method here
    # Your code here
}

Need a hint?

Inside Car, write override func description() -> String and return the new string.

4

Create Car instance and print results

Create an instance of Car called myCar. Print the result of calling myCar.description() and then print myCar.type.

Swift

class Vehicle {
    func description() -> String {
        return "This is a vehicle"
    }
    var type: String {
        return "Generic Vehicle"
    }
}

class Car: Vehicle {
    override var type: String {
        return "Car"
    }
    
    override func description() -> String {
        return "This is a car"
    }
}

# Create instance myCar and print description() and type
# Your code here

Need a hint?

Create let myCar = Car(). Use print(myCar.description()) and print(myCar.type) to show the results.