如何從父母委托給多個不同的孩子？

我有這個方案：

• 家庭控制器
  • 導航控制器
    • Step1（NavigationController 的子級）
    • Step2（NavigationController 的子級）

我的問題是我不知道如何將資訊從父母傳遞給所有不同的孩子，因為當我將代表分配給孩子時，總是取最后一個。所以如果我打電話給委托，只有我添加的最后一個孩子會收到資訊

一些基本代碼：

class HomeController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        addSubview(showSteps)
    }
    @objc func showSteps() {
        let controller = NavigationController()
        self.present(controller, animated: true, completion: nil)
    }
}


protocol UserProtocol: AnyObject {
    func userHasChanged(_ user: User?)
}


class NavigationController: UIViewController {

    var user: User?
    weak var delegate: UserProtocol?
    
    override func viewDidLoad() {
        
        // all step childs are differents
        let step1 = Step1()
        addStep(step: step1)
        delegate = step1
        
        let step2 = Step2()
        addStep(step: step2)
        delegate = step2
        
        let step3 = Step3()
        addStep(step: step3)
        delegate = step3
        
        let step4 = Step4()
        addStep(step: step4)
        delegate = step4
        
    }
    
    func addStep(step: UIViewController){
        self.addChild(step)
        step.willMove(toParent: self)
        view.addSubview(step.view)
        step.didMove(toParent: self)
    }
    
    func userHasChanged(_ user: User?){
        // this observe new user data from firebase
        Service.shared.fetchUserData(uid: "XXX") { user in
            self.user = user
            // send new data to childs
            // ONLY SEND TO CHILD4, (THE LAST ONE OBVIOUSLY)
            self.delegate?.userHasChanged(user)
        }
    }

}

// that is a child example
class Step1: UIViewController, UserProtocol {
    
    var user: User?
    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
    func tripHasChanged(_ new_user: User?) {
        print("changed1")
        self.user = new_user
    }

}

class Step2: UIViewController, UserProtocol {
    
    var user: User?
    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
    func tripHasChanged(_ new_user: User?) {
        print("changed2")
        self.user = new_user
    }

}

class Step3: UIViewController, UserProtocol {
    
    var user: User?
    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
    func tripHasChanged(_ new_user: User?) {
        print("changed3")
        self.user = new_user
    }

}

class Step4: UIViewController, UserProtocol {
    
    var user: User?
    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
    func tripHasChanged(_ new_user: User?) {
        print("changed4")
        self.user = new_user
    }

}

*只列印“changed4”

我的問題：

我該如何使用一個委托（可能是陣列？）向所有不同的孩子發送資料？有可能，屬于好的做法嗎？

謝謝！

uj5u.com熱心網友回復：

您可以創建一個委托陣列......但這實際上不是委托/協議設計模式。

您也可以采用NotificationCenteraddObserver / post 通知方法...但這更適合不一定“受當前類控制”的多個物件。

對于您的情況 - 多個子視圖控制器都需要基于同一事件“做某事”，更好的方法可能是創建一個“基礎”視圖控制器并制作該基礎的每個“步驟”子類。

這是一個簡單的例子......

// this is our "Step" base view controller
//  creates the "user" property
//  defines the "userHasChanged()" method
class StepBaseViewController: UIViewController {

    var user: String?
    func userHasChanged(_ new_user: String) {
        user = new_user
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // we can do anything that may be
        //  "common" to all "Steps"
    }

}

您創建子類的任何視圖控制器StepBaseViewController現在都將具有一個user屬性和一個默認方法來處理userHasChanged。此外，步驟中“常見”的任何內容（例如標簽、按鈕等 UI 元素）都可以在viewDidLoad().

現在您的 4“步驟”類變為：

class Step1: StepBaseViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        // setup specific to this "Step"
    }
    override func userHasChanged(_ new_user: String) {
        super.userHasChanged(new_user)
        print("User changed to:", self.user, "in:", self)
        // do something specific to Step 1
    }
}
class Step2: StepBaseViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        // setup specific to this "Step"
    }
    override func userHasChanged(_ new_user: String) {
        super.userHasChanged(new_user)
        print("User changed to:", self.user, "in:", self)
        // do something specific to Step 2
    }
}
class Step3: StepBaseViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        // setup specific to this "Step"
    }
    override func userHasChanged(_ new_user: String) {
        super.userHasChanged(new_user)
        print("User changed to:", self.user, "in:", self)
        // do something specific to Step 3
    }
}
class Step4: StepBaseViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        // setup specific to this "Step"
    }
    override func userHasChanged(_ new_user: String) {
        super.userHasChanged(new_user)
        print("User changed to:", self.user, "in:", self)
        // do something specific to Step 4
    }
}

NavigationController這是您展示如何使用這種方法的修改版本：

class NavigationController: UIViewController {

    // we'll simulate the user changing
    //  so on first tap the user will become "User 1"
    //  on next tap user will become "User 2"
    //  on next tap user will become "User 3"
    // and so on
    var n: Int = 0
    var user: String = ""
    
    override func viewDidLoad() {
        
        // all step childs are differents
        let step1 = Step1()
        addStep(step: step1)
        
        let step2 = Step2()
        addStep(step: step2)
        
        let step3 = Step3()
        addStep(step: step3)
        
        let step4 = Step4()
        addStep(step: step4)
        
    }
    
    func addStep(step: UIViewController){
        self.addChild(step)
        step.willMove(toParent: self)
        view.addSubview(step.view)
        step.didMove(toParent: self)
    }

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
        // simulate the "user changed" event
        n  = 1
        self.user = "User \(n)"
        self.children.forEach { child in
            if let vc = child as? StepBaseViewController {
                vc.userHasChanged(self.user)
            }
        }
    }

}

加載后，NavigationController點擊 3 次會導致此除錯控制臺輸出：

User changed to: Optional("User 1") in: <MyProj.Step1: 0x7fbd7a21caf0>
User changed to: Optional("User 1") in: <MyProj.Step2: 0x7fbd7a21c480>
User changed to: Optional("User 1") in: <MyProj.Step3: 0x7fbd7a21d480>
User changed to: Optional("User 1") in: <MyProj.Step4: 0x7fbd7a21dca0>
User changed to: Optional("User 2") in: <MyProj.Step1: 0x7fbd7a21caf0>
User changed to: Optional("User 2") in: <MyProj.Step2: 0x7fbd7a21c480>
User changed to: Optional("User 2") in: <MyProj.Step3: 0x7fbd7a21d480>
User changed to: Optional("User 2") in: <MyProj.Step4: 0x7fbd7a21dca0>
User changed to: Optional("User 3") in: <MyProj.Step1: 0x7fbd7a21caf0>
User changed to: Optional("User 3") in: <MyProj.Step2: 0x7fbd7a21c480>
User changed to: Optional("User 3") in: <MyProj.Step3: 0x7fbd7a21d480>
User changed to: Optional("User 3") in: <MyProj.Step4: 0x7fbd7a21dca0>

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