StackView show/hide arranged subview

class StackViewController: UIViewController {

    let stackView: UIStackView = {
        let v = UIStackView()
        v.axis = .vertical
        return v
    }()

    override func viewDidLoad() {
        super.viewDidLoad()

        // two views to add to the stack view
        let v1 = UIView()
        let v2 = UIView()

        // a "container" for the stack view
        let stackContainer = UIView()

        v1.backgroundColor = .red
        v2.backgroundColor = .green
        stackContainer.backgroundColor = .yellow

        stackView.translatesAutoresizingMaskIntoConstraints = false
        stackContainer.translatesAutoresizingMaskIntoConstraints = false

        stackView.addArrangedSubview(v1)
        stackView.addArrangedSubview(v2)

        stackContainer.addSubview(stackView)
        view.addSubview(stackContainer)

        let g = view.safeAreaLayoutGuide

        NSLayoutConstraint.activate([

            // stack view "container" view Top: 40 / centerX
            stackContainer.topAnchor.constraint(equalTo: g.topAnchor, constant: 40.0),
            stackContainer.centerXAnchor.constraint(equalTo: g.centerXAnchor),

            // stackView all 4 sides to "container" view
            stackView.topAnchor.constraint(equalTo: stackContainer.topAnchor),
            stackView.leadingAnchor.constraint(equalTo: stackContainer.leadingAnchor),
            stackView.trailingAnchor.constraint(equalTo: stackContainer.trailingAnchor),
            stackView.bottomAnchor.constraint(equalTo: stackContainer.bottomAnchor),

            // both arranged subviews 240x160
            v1.widthAnchor.constraint(equalToConstant: 240.0),
            v1.heightAnchor.constraint(equalToConstant: 160.0),

            v2.widthAnchor.constraint(equalTo: v1.widthAnchor),
            v2.heightAnchor.constraint(equalTo: v1.heightAnchor),

        ])

        let t = UITapGestureRecognizer(target: self, action: #selector(gotTap(_:)))
        view.addGestureRecognizer(t)

    }

    @objc func gotTap(_ sender: Any?) -> Void {

        // get a reference to the 2nd arranged subview
        guard let v = stackView.arrangedSubviews.last else {
            return
        }

        // hide / show
        v.isHidden.toggle()

    }

}