UILabel extension with regular/bold font that works

finalUILabelExtension.swift

extension UILabel {    
    @objc var substituteFontName: String {
        get {
            return font.fontName
        }
        set {
            // Set custom font unless the original font is a bold font.
            if font.fontName.range(of: "Medium") == nil {
                font = UIFont(name: newValue, size: font.pointSize)
            }
        }
    }
    @objc var substituteBoldFontName: String {
        get {
            return font.fontName
        }
        set {
            // Set custom font only if the original font is a bold font.
            if font.fontName.range(of: "Medium") != nil {
                font = UIFont(name: newValue, size: font.pointSize)
            }
        }
    }
}