如何将数据从View Controller传递到Container View？

Question

我正在尝试将数据从ViewController传递到其中的容器。当我按下按钮时，委托将数据发送到容器，但是容器会调整大小。我将如何阻止这种情况的发生。 我在考虑一个prepareForSegue函数，但是我不知道如何实现它，但是我不知道这是否是解决方案。

protocol VCDelegate {

    func passData(theData1:String)

}

class ViewController: UIViewController {

    var delegate : VCDelegate?

    @IBAction func sendTextToContainer(_ sender: Any) {

        let ViewC = self.storyboard!.instantiateViewController(withIdentifier: "ViewController") as! ViewController

        let ContainerV = self.storyboard!.instantiateViewController(withIdentifier: "ContainerView") as! ContainerView

        self.present(ContainerV,animated:true,completion: nil)

        ViewC.delegate = ContainerV

        ViewC.delegate?.passData(theData1:"Hello")
    } 
}

class ContainerView: UIViewController, VCDelegate {

    func passData(theData1: String) {

        print(theData1)
        theText.text = theData1

    }

    @IBOutlet weak var theText: UILabel!

    override func viewWillAppear(_ animated: Bool) {

    }

}

Answer 1

您正在实例化子视图控制器的新的第二个实例。但是，如果您在IB中创建了“容器”，则已经为您实例化了。

父视图控制器有两种方式将数据传递给子视图。您可以在prepare(for:sender:)中传递初始数据：

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if let destination = segue.destination as? SecondViewControllerProtocol {
        destination.passData(string: "Initial value")
    }
}

如果您以后想要更新它，可以获取相关的children：

@IBAction func didTapButton(_ sender: Any) {
    for child in children {
        if let child = child as? SecondViewControllerProtocol {
            child.passData(string: "Updated value")
        }
    }
}

（如果您愿意，显然您也可以保存在prepare(for:sender:)期间捕获的参考。）

然后，第二个视图控制器可以相应地更新其标签：

protocol SecondViewControllerProtocol {
    func passData(string: String) 
}

class SecondViewController: UIViewController {
    @IBOutlet weak var label: UILabel!

    private var string: String?

    override func viewDidLoad() {
        super.viewDidLoad()

        // this is in case you passed the data before the label was hooked up

        label.text = string
    }
}

extension SecondViewController: SecondViewControllerProtocol {
    func passData(string: String) {
        self.string = string

        guard let label = label else { return }

        UIView.transition(with: label, duration: 0.25, options: .transitionCrossDissolve, animations: {
            label.text = string
        }, completion: nil)
    }
}

结果是：