在ChildViewController中添加ChildViewController并执行按钮操作

class ChildViewController: UIViewController {
    // 创建一个按钮
    let addButton = UIButton(type: .system)

    override func viewDidLoad() {
        super.viewDidLoad()

        // 设置按钮的标题和位置
        addButton.setTitle("添加ChildViewController", for: .normal)
        addButton.frame = CGRect(x: 100, y: 100, width: 200, height: 50)

        // 为按钮添加点击事件
        addButton.addTarget(self, action: #selector(addChildViewController), for: .touchUpInside)

        // 将按钮添加到视图中
        view.addSubview(addButton)
    }

    @objc func addChildViewController() {
        // 在按钮点击事件中执行添加ChildViewController的操作
        let childVC = ChildViewController()
        addChild(childVC)
        childVC.view.frame = CGRect(x: 0, y: 200, width: view.frame.width, height: view.frame.height - 200)
        view.addSubview(childVC.view)
        childVC.didMove(toParent: self)
    }
}