quick UIFontDescriptor test

// quick UIFontDescriptor test

class AvenirTestVC: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        var avFamilyName: String = ""

        // let's make sure we have the Avenir Next font family
        for family in UIFont.familyNames {
            if family ==  "Avenir Next" {
                avFamilyName = family
                break
            }
        }

        if avFamilyName.isEmpty {
            fatalError("Avenir Next font family not found!!!")
        }

        let stackView = UIStackView()
        stackView.axis = .vertical
        stackView.spacing = 8

        stackView.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(stackView)

        let g = view.safeAreaLayoutGuide

        NSLayoutConstraint.activate([

            stackView.topAnchor.constraint(equalTo: g.topAnchor, constant: 40.0),
            stackView.leadingAnchor.constraint(equalTo: g.leadingAnchor, constant: 16.0),
            stackView.trailingAnchor.constraint(equalTo: g.trailingAnchor, constant: -16.0),

        ])

        let weights: [UIFont.Weight] = [
            .light, .regular, .medium, .semibold, .bold, .heavy,
        ]

        weights.forEach { w in
            let thisDescriptor = UIFontDescriptor(fontAttributes: [
                UIFontDescriptor.AttributeName.family: avFamilyName,
                UIFontDescriptor.AttributeName.traits: [
                    UIFontDescriptor.TraitKey.weight: w
                ]
            ])
            let fnt: UIFont = UIFont(descriptor: thisDescriptor, size: 28)
            let label = UILabel()
            label.font = fnt
            label.text = fnt.fontName
            label.textAlignment = .center
            stackView.addArrangedSubview(label)
        }

    }

}