ObserverPatternInSwift

observerPatternExample.swift

class Subject {
    var list: [Adventurer] = []
    func add(adventurer: Adventurer) {
        list.append(adventurer)
    }
    func remove(adventurer: Adventurer) {
        if let index = list.firstIndex(where: { $0 == adventurer}) {
            list.remove(at: index)
        }
    }
    func sendQuestions(question: String) {}
}

class Association: Subject {
    override func sendQuestions(question: String) {
        print("send questions")
        list.forEach { $0.getQuestions(question: question) }
    }
}

class Adventurer: Hashable {
    var id: String
    var name: String
    init(id: String, name: String) {
        self.id = id
        self.name = name
    }

    func hash(into hasher: inout Hasher) {
        hasher.combine(id)
        hasher.combine(name)
    }

    static func == (lhs: Adventurer, rhs: Adventurer) -> Bool {
        return lhs.id == rhs.id
    }
    
    func getQuestions(question: String) {}
}

class Bard: Adventurer {
    override func getQuestions(question: String) {
        print("Bard get question")
    }
}

class Gunman: Adventurer {
    override func getQuestions(question: String) {
        print("Gunman get question")
    }
}

class Lancer: Adventurer {
    override func getQuestions(question: String) {
        print("Lancer get question")
    }
}


let lancer = Lancer(id: UUID().uuidString, name: "lancer")
let bard = Bard(id: UUID().uuidString, name: "bard")
let gunman = Gunman(id: UUID().uuidString, name: "gunman")
let association = Association()
association.add(adventurer: lancer)
association.add(adventurer: bard)
association.add(adventurer: gunman)
association.sendQuestions(question: "ChatGPT can substitute the work of people :D")