Question

我正在尝试获取子视图控制器，它显示在主视图控制器底部的视图容器中。当我按下孩子中的按钮时，“从基本VC按下的按钮”打印到控制台，但是“从主VC按下的热按钮”没有。我需要打印要在主View Controller中调用的第二条消息的函数。这是相关的BasicViewController代码：

protocol BasicVCDelegate: class {
    func warmButton()
}

class BasicViewController: UIViewController {
    weak var BasicVCDelegate: BasicVCDelegate?

    @IBOutlet weak var warmButton: UIButton!

    @IBAction func warmButton(sender: AnyObject) {
        print("Button pressed from Basic VC")
        BasicVCDelegate?.warmButton()
    }
}

来自ViewController.swift

class ViewController: UIViewController, UITableViewDataSource, UITableViewDelegate, BasicVCDelegate {
    override func viewDidLoad() {
        pauseButton.isEnabled = false

        hideAll();
        self.basicContainer.isUserInteractionEnabled = true;
        self.basicContainer.isHidden = false;

        self.timerLabel.text = String("00:00:00");

        eventTable.dataSource = self
        eventTable.delegate = self

        loadEvents(event: "timer start")
        super.viewDidLoad()
    }

    // CREATE SEGUEs
    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        if let nav = segue.destination as? UINavigationController, let classBasicVC = nav.topViewController as? BasicViewController {
            classBasicVC.BasicVCDelegate = self
        }
    }

    // FUNCTIONS FOR BASIC VIEW CONTROLLER TO REFERENCE
    func warmButton() {
        print("Warm button pressed from main VC")
    }
}

编辑：从下面的每个人看来，ViewController中的以下代码部分似乎导致了问题（永远不会调用if语句中的行）：

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if let nav = segue.destination as? UINavigationController, let classBasicVC = nav.topViewController as? BasicViewController {
        classBasicVC.basicVCDelegate = self
    }
}

这可能是由于我对代表和prepareforsegue功能的不熟悉。需要帮助找出应该遵循的“if let”

编辑2：根据某些用户的建议（仍未达到打印声明），将以上代码替换为以下代码：

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if let nav = segue.destination as? BasicViewController, let classBasicVC = nav.basicVCDelegate {
        print("got here!!")
    }
}

最终编辑：谢谢您的帮助！在一些游戏之后，以下工作（除了在我解决它时改变为错误的警告 - 我可以忍受警告）。

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if let nav = segue.destination as? BasicViewController, let classBasicVC = nav as? BasicViewController? {
        classBasicVC?.basicVCDelegate = self
    }
}

Answer 1

应该是这而不是您上次编辑的代码：

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if let classBasicVC = segue.destination as? BasicViewController {
        classBasicVC.basicVCDelegate = self
    }
}

Answer 2

您尚未将按钮的委托分配给ViewController

将此添加到ViewController的viewDidLoad

    override func viewDidLoad() {
    //other code 
    yourButton.BasicVCDelegate = self
    }

对于委托变量使用驼峰案例也是一种很好的做法，例如basicVCDDelegate

Swift委托不在父级中调用函数

2 个答案: