Protocol declaration syntax in Swift - Mini Project: Build & Apply

Protocol declaration syntax

📖 Scenario: Imagine you are creating a simple app that manages different types of vehicles. You want to make sure all vehicles can start and stop, but each vehicle might do it differently.

🎯 Goal: You will create a Vehicle protocol that requires two functions: start() and stop(). Then, you will create a struct that follows this protocol.

📋 What You'll Learn

Create a protocol named Vehicle

Add two function declarations inside the protocol: start() and stop()

Create a struct named Car that conforms to the Vehicle protocol

Implement the start() and stop() functions inside Car

Print messages when start() and stop() are called

💡 Why This Matters

🌍 Real World

Protocols are used in apps to define common behaviors for different types, like vehicles, animals, or user interface elements.

💼 Career

Understanding protocols is essential for Swift developers to write flexible and reusable code, especially in app development for iOS and macOS.

1

Create the Vehicle protocol

Write a protocol named Vehicle with two function declarations: start() and stop(). Do not add any code inside the functions.

Swift

# Write the protocol Vehicle with start() and stop() function declarations
// Your code here

Need a hint?

Use the protocol keyword followed by the protocol name. Inside curly braces, declare the functions without bodies.

2

Create the Car struct conforming to Vehicle

Create a struct named Car that conforms to the Vehicle protocol.

Swift

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

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

Need a hint?

Use struct Car: Vehicle to declare the struct and protocol conformance.

3

Implement start() and stop() in Car

Inside the Car struct, implement the start() function to print "Car started" and the stop() function to print "Car stopped".

Swift

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

struct Car: Vehicle {
    // Implement start() to print "Car started"
    // Implement stop() to print "Car stopped"
    // Your code here
}

Need a hint?

Use print("Car started") inside start() and print("Car stopped") inside stop().

4

Create a Car instance and call start() and stop()

Create a variable named myCar as an instance of Car. Then call myCar.start() and myCar.stop() to print the messages.

Swift

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

struct Car: Vehicle {
    func start() {
        print("Car started")
    }
    func stop() {
        print("Car stopped")
    }
}

// Create myCar instance and call start() and stop()
// Your code here

Need a hint?

Create myCar with let myCar = Car(). Then call myCar.start() and myCar.stop().