This UIViewController extension provides methods to easily embed and detach a child view controller, managing its view hierarchy and layout within a parent view controller.

UIViewController+ChildManagement.swift

// details: https://developer.apple.com/documentation/uikit/creating-a-custom-container-view-controller

extension UIViewController {

    @objc(attachToParentViewController:layout:)
    public func attach(toParent parent: UIViewController?, layout: (@MainActor (UIView) -> Void)? = nil) {
        guard let parent else {
            return
        }

        parent.addChild(self)

        if let contentView = view {
            parent.view.addSubview(contentView)

            if let layout {
                layout(contentView)
            } else {
                contentView.frame = parent.view.bounds
                contentView.translatesAutoresizingMaskIntoConstraints = true
                contentView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
            }
        }

        didMove(toParent: parent)
    }

    @objc(detachFromParentViewController)
    public func detachFromParent() {
        willMove(toParent: nil)
        view.removeFromSuperview()
        removeFromParent()
    }
}