Change Font name Without change font size

Label Font

UILabel.appearance().defaultFont =  UIFont.systemFont(ofSize: 15/*Any Value*/, weight: UIFontWeightThin)

extension UILabel{
    dynamic var defaultFont: UIFont? {
        get { return self.font }
        set {
          let sizeOfOldFont = self.font.pointSize
          let fontNameOfNewFont = newValue?.fontName
          self.font = UIFont(name: fontNameOfNewFont!, size: sizeOfOldFont)
        }
    }
    
}