Protocol Basics in Swift

// Protocol definition
protocol Vehicle {
    var numberOfWheels: Int { get }
    var color: String { get set }

    func start()
    func stop()
}

// Protocol adoption
struct Car: Vehicle {
    let numberOfWheels = 4
    var color: String

    func start() {
        print("Engine started")
    }

    func stop() {
        print("Brakes applied")
    }
}

// Multiple protocols
protocol Named {
    var name: String { get }
}

protocol Aged {
    var age: Int { get }
}

struct Person: Named, Aged {
    let name: String
    let age: Int
}