really hoping this will work out of the box in future versions

UIFont+FontWeight.swift

public extension UIFont {
    public class func systemFont(ofSize fontSize: CGFloat, weight: UIFontWeight) -> UIFont {
        return .systemFont(ofSize: fontSize, weight: weight.floatValue)
    }
    
    public class func monospacedDigitSystemFont(ofSize fontSize: CGFloat, weight: UIFontWeight) -> UIFont {
        return .monospacedDigitSystemFont(ofSize: fontSize, weight: weight.floatValue)
    }
}

public enum UIFontWeight {
    case ultralight
    case thin
    case light
    case regular
    case medium
    case semibold
    case bold
    case black
    case heavy
    
    public var floatValue: CGFloat {
        switch self {
        case .ultralight:
            return UIFontWeightUltraLight
        case .thin:
            return UIFontWeightThin
        case .light:
            return UIFontWeightLight
        case .regular:
            return UIFontWeightRegular
        case .medium:
            return UIFontWeightMedium
        case .semibold:
            return UIFontWeightSemibold
        case .bold:
            return UIFontWeightBold
        case .black:
            return UIFontWeightBlack
        case .heavy:
            return UIFontWeightHeavy
        }
    }
}