委托从子视图到主视图的更改

Question

我有UIViewController和mainView和ChildView。 我想从ChildView更改mainView中的标签

我添加的孩子

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-其视图，其中显示childView

我试图用委托在ChildView中做到这一点：

protocol UserDelegate {
    func changeName(name: String)
}

class ChildView: UIViewController {

     var userDelegate: UserDelegate?

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

在MainView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)!"
    }
}

Answer 1

问题在于您需要提供一个ChildView实例，并在另一个ChildView实例上设置一个委托。 因此，屏幕上显示的子视图与调用委托的视图不同。 在添加ChildView时设置委托：

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，为防止保留周期，请对委托使用weak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viewDidLoad实现：

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