GoF_Composite.swift

import Foundation

protocol Alphabet {
    func compositeAction()
}

class A {
    let aProperty = "A"
}

extension A: Alphabet {
    func compositeAction() {
        print(aProperty)
    }
}

class B {
    let bProperty = "B"
}

extension B: Alphabet {
    func compositeAction() {
        print(bProperty)
    }
}

class AlphabetSet {
    var alphabets: [Alphabet]
    init(_ alphabets: [Alphabet] = []) {
        self.alphabets = alphabets
    }
}

extension AlphabetSet: Alphabet {
    func compositeAction() {
        alphabets.forEach {
            $0.compositeAction()
        }
    }
}

AlphabetSet([A(), AlphabetSet([A(), B(), A(), A(), B()]), A()]).compositeAction()