Why protocol-oriented programming matters in Swift - See It in Action

Why protocol-oriented programming matters

📖 Scenario: Imagine you are building a simple app that manages different types of vehicles. Each vehicle can start and stop, but they do these actions differently. You want a clean way to organize this behavior so you can add more vehicle types easily in the future.

🎯 Goal: You will create a protocol to define common vehicle actions, then make different vehicle types conform to this protocol. This shows why protocol-oriented programming helps write flexible and reusable code.

📋 What You'll Learn

Create a protocol named Vehicle with two methods: start() and stop()

Create a struct called Car that conforms to Vehicle and implements start() and stop()

Create a struct called Bicycle that conforms to Vehicle and implements start() and stop()

Create an array called vehicles that holds both Car and Bicycle instances

Use a for loop to call start() on each vehicle in the vehicles array

Print output messages showing each vehicle starting and stopping

💡 Why This Matters

🌍 Real World

Protocol-oriented programming is used in Swift to write clean, reusable code that works well with many types. It helps apps stay organized and easy to extend.

💼 Career

Understanding protocols is essential for Swift developers. It is a core skill for building apps that are maintainable and scalable in professional iOS development.

1

Create the Vehicle protocol

Create a protocol named Vehicle with two methods: start() and stop().

Swift

# Define the Vehicle protocol with start() and stop() methods
// Your code here

Need a hint?

Protocols define a blueprint of methods. Use protocol Vehicle {} and add func start() and func stop() inside.

2

Create Car and Bicycle structs conforming to Vehicle

Create a struct called Car that conforms to Vehicle and implements start() and stop(). Then create a struct called Bicycle that also conforms to Vehicle and implements start() and stop().

Swift

protocol Vehicle {
    func start()
    func stop()
}

// Create Car struct conforming to Vehicle
// Create Bicycle struct conforming to Vehicle
// Your code here

Need a hint?

Use struct Car: Vehicle {} and implement the two methods with print statements. Do the same for Bicycle.

3

Create an array of vehicles

Create an array called vehicles that holds instances of Car and Bicycle.

Swift

protocol Vehicle {
    func start()
    func stop()
}

struct Car: Vehicle {
    func start() {
        print("Car is starting its engine.")
    }
    func stop() {
        print("Car has stopped.")
    }
}

struct Bicycle: Vehicle {
    func start() {
        print("Bicycle rider starts pedaling.")
    }
    func stop() {
        print("Bicycle has stopped.")
    }
}

// Create an array called vehicles with Car and Bicycle instances
// Your code here

Need a hint?

Use let vehicles: [Vehicle] = [Car(), Bicycle()] to create the array.

4

Start all vehicles and print output

Use a for loop with variable vehicle to iterate over vehicles and call start() on each. Then print a message showing each vehicle started.

Swift

protocol Vehicle {
    func start()
    func stop()
}

struct Car: Vehicle {
    func start() {
        print("Car is starting its engine.")
    }
    func stop() {
        print("Car has stopped.")
    }
}

struct Bicycle: Vehicle {
    func start() {
        print("Bicycle rider starts pedaling.")
    }
    func stop() {
        print("Bicycle has stopped.")
    }
}

let vehicles: [Vehicle] = [Car(), Bicycle()]

// Use a for loop to call start() on each vehicle
// Your code here

Need a hint?

Use for vehicle in vehicles { vehicle.start() } to call start on each vehicle.