Protocol as types in Swift - Mini Project: Build & Apply

Using Protocol as Types in Swift

📖 Scenario: You are building a simple app that manages different types of vehicles. Each vehicle can start its engine, but the way it starts might differ. You want to use a protocol to represent any vehicle type and treat them uniformly.

🎯 Goal: Create a protocol called Vehicle with a startEngine() method. Then create two structs, Car and Motorcycle, that conform to Vehicle. Finally, use the protocol as a type to store different vehicles in an array and start their engines.

📋 What You'll Learn

Create a protocol named Vehicle with a method startEngine() that returns a String.

Create a struct Car that conforms to Vehicle and implements startEngine() returning "Car engine started".

Create a struct Motorcycle that conforms to Vehicle and implements startEngine() returning "Motorcycle engine started".

Create an array called vehicles of type [Vehicle] containing one Car and one Motorcycle.

Use a for loop to call startEngine() on each vehicle in vehicles and print the result.

💡 Why This Matters

🌍 Real World

Protocols let you write flexible code that can work with many types sharing the same behavior, like different vehicles in a transport app.

💼 Career

Understanding protocols and using them as types is key for Swift developers to write clean, reusable, and scalable code.

1

Create the Vehicle protocol

Create a protocol called Vehicle with a method startEngine() that returns a String.

Swift

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

Need a hint?

Use the protocol keyword and define startEngine() as a function returning String.

2

Create Car and Motorcycle structs conforming to Vehicle

Create a struct called Car that conforms to Vehicle and implements startEngine() returning "Car engine started". Also create a struct called Motorcycle that conforms to Vehicle and implements startEngine() returning "Motorcycle engine started".

Swift

protocol Vehicle {
    func startEngine() -> String
}

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

Need a hint?

Define structs with struct Name: Vehicle and implement startEngine() returning the exact strings.

3

Create an array of Vehicle type

Create an array called vehicles of type [Vehicle] containing one Car() and one Motorcycle().

Swift

protocol Vehicle {
    func startEngine() -> String
}

struct Car: Vehicle {
    func startEngine() -> String {
        return "Car engine started"
    }
}

struct Motorcycle: Vehicle {
    func startEngine() -> String {
        return "Motorcycle engine started"
    }
}

// Create an array vehicles of type [Vehicle] with Car() and Motorcycle()
// Your code here

Need a hint?

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

4

Loop through vehicles and print engine start messages

Use a for loop with variable vehicle to iterate over vehicles. Inside the loop, call startEngine() on vehicle and print the returned string.

Swift

protocol Vehicle {
    func startEngine() -> String
}

struct Car: Vehicle {
    func startEngine() -> String {
        return "Car engine started"
    }
}

struct Motorcycle: Vehicle {
    func startEngine() -> String {
        return "Motorcycle engine started"
    }
}

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

// Use a for loop to print startEngine() result for each vehicle
// Your code here

Need a hint?

Use for vehicle in vehicles and print(vehicle.startEngine()).