UIStackView with custom spacing after arranged subview

UIStackView+Extensions.swift

extension UIStackView {
    func setSpacing(_ spacing: CGFloat, after arrangedSubview: UIView) {
        guard let index = arrangedSubviews.firstIndex(of: arrangedSubview) else { return }

        let spaceView = UIView()
        spaceView.translatesAutoresizingMaskIntoConstraints = false

        switch axis {
        case .horizontal:
            spaceView.widthAnchor.constraint(equalToConstant: spacing).isActive = true
        case .vertical:
            spaceView.heightAnchor.constraint(equalToConstant: spacing).isActive = true
        @unknown default:
            fatalError()
        }

        insertArrangedSubview(spaceView, at: index + 1)
    }
}