iOS Swift，协议(protocol)中有一个公共(public)方法，两个ViewControllers中有两个实现，如何确定调用哪个ViewControllers方法？

Question

我有一个协议(protocol)

protocol HandleEmbedController: class {
    func printMsg()
}

和 2 个容器 View 和 2 个相应的 ViewControllers

class EnemyBaseVC: UIViewController, HandleEmbedController {

    override func viewDidLoad() {
        super.viewDidLoad()
    }

    var value1 = ""

    func printMsg(){
        print("printing some embedded message")
    }

} 

和

class EnemyBase2VC: UIViewController, HandleEmbedController {

    func printMsg() {
        print("enemy base 2 message")
    }

    override func viewDidLoad() {
        super.viewDidLoad()

    }

}

并且都使用协议(protocol) HandleEmbedController 并实现 printMsg 功能。

在我的主 ViewController 中

class HomeBaseVC: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

    }

    var handleEmbedController:HandleEmbedController?

    @IBAction func onclick(_ sender: UIButton) {

        handleEmbedController?.printMsg()
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

        if (segue.identifier == "embedseg"){
            if let embed = segue.destination as? EnemyBaseVC     {
                self.handleEmbedController = embed
            }
        }

        if (segue.identifier == "embedseg2"){
            if let embed = segue.destination as? EnemyBase2VC     {
                self.handleEmbedController = embed
            }
        }


    }
}

当按钮被点击时，EnemyBaseVC 方法总是被调用并打印

printing some embedded message

有什么方法可以决定调用哪个方法吗？

更新

Answer 1

如果您有两个容器 View ，两个转场都将在加载时触发，并且 handleEmbedController 将引用最后加载的一个 ViewController。

如果您有一些逻辑来决定应该引用哪个，那么您可以使用它来决定将引用哪个 ViewController，如下所示:

class HomeBaseVC: UIViewController {

override func viewDidLoad() {
    super.viewDidLoad()

}

var handleEmbedController:HandleEmbedController?

//  comes from your decision logic
var decisionMaker: Bool = false

@IBAction func onclick(_ sender: UIButton) {

    handleEmbedController?.printMsg()
}

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

    if (segue.identifier == "embedseg"),
        let embed = segue.destination as? EnemyBaseVC,
        decisionMaker {
        self.handleEmbedController = embed
    }

    else if (segue.identifier == "embedseg2"),
        let embed = segue.destination as? EnemyBase2VC,
        !decisionMaker {
        self.handleEmbedController = embed
    }
  }
}

请注意，这会在加载时设置 handleEmbedController，如果您需要更复杂的行为，您最好在 segue 之外的其他地方处理 handleEmbedController 的分配。

由于这是您的基础 ViewController 必须与多个对象通信的场景，您还可以使用通知而不是委托(delegate)。这样，您可以决定在用户​​点击按钮时发送哪条消息。您的基本 ViewController 看起来像这样

class HomeBaseVC: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

    }

    //  comes from your decision logic
    var decisionMaker: Bool = true

    @IBAction func onclick(_ sender: UIButton) {
        NotificationCenter.default.post(name: NSNotification.Name(rawValue: "BUTTON_WAS_TAPPED"), object: nil, userInfo: ["decision" : decisionMaker])
    }
}

虽然敌人的 ViewController 看起来像这样(第二个除了要处理的决策值外是一样的)

class EnemyBaseVC: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        NotificationCenter.default.addObserver(forName: NSNotification.Name(rawValue: "BUTTON_WAS_TAPPED"),
                                           object: nil,
                                           queue: nil) { notification in
                                                if let userInfo = notification.userInfo,
                                                    let decision = userInfo["decision"] as? Bool,
                                                    decision {
                                                        self.printMsg()
                                                }
        }
    }

    var value1 = ""

    private func printMsg(){
        print("printing some embedded message")
    }
}