swift - 委托(delegate)从 subview 到主 View 的更改

我有带主视图和子视图的UIViewController。
我要从ChildView更改mainView中的标签

我添加的子项

let to = ChildView()
self.addChild(to)
self.mainView.addSubview(to.view)
self.mainViewConstraint.constant = to.view.frame.height
to.view.frame = self.mainView.bounds
to.view.autoresizingMask = [.flexibleWidth, .flexibleHeight]

mainView-它的视图，其中显示childView
我试着和代表一起做
在ChildView中：

protocol UserDelegate {
    func changeName(name: String)
}

class ChildView: UIViewController {

     var userDelegate: UserDelegate?

    @IBAction func changeNameBtn(_ sender: UIButton) {
        self.userDelegate?.changeName(name: "TestChanges")
    }
}

在主视图中：

class MainView: UIViewController, UserDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()
        let ChildView = ChildView()
        ChildView.userDelegate = self
    }

    func changeName(name: String) {
        self.helloLabel.text = "Hello \(name)!"
    }
}

最佳答案

问题是您呈现ChildView的一个实例，并在ChildView的另一个实例上设置委托。因此，屏幕上显示的子视图与调用委托的子视图不同。添加ChildView时设置代理：

let to = ChildView()
self.addChild(to)
self.mainView.addSubview(to.view)
self.mainViewConstraint.constant = to.view.frame.height

// set the delegate here
to.userDelegate = self.mainView

to.view.frame = self.mainView.bounds
to.view.autoresizingMask = [.flexibleWidth, .flexibleHeight]

此外，要防止保留循环，请使用对委托的引用：

protocol UserDelegate: AnyObject {
    func changeName(name: String)
}

class ChildView: UIViewController {

    weak var userDelegate: UserDelegate?

    @IBAction func changeNameBtn(_ sender: UIButton) {
        self.userDelegate?.changeName(name: "TestChanges")
    }
}

最后，您可以从主视图中删除weak实现：

class MainView: UIViewController, UserDelegate {
    // this should be enough
    func changeName(name: String) {
        self.helloLabel.text = "Hello \(name)!"
    }
}

关于swift - 委托(delegate)从 subview 到主 View 的更改，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/55947999/