如何获取字体大小或UIFont实例的粗体版本

let font = UIFont.systemFont(ofSize: 17)
let fontSize = font.pointSize

let font = UIFont.systemFont(ofSize: 17)
let boldFont = font.bold()

let fontName = "YourFontName"
let fontSize = 17
let font = UIFont(name: fontName, size: fontSize)
let boldFont = font?.bold()

let fontSize = 17
let boldSystemFont = UIFont.boldSystemFont(ofSize: fontSize)