你如何使用NSAttributedString？

// 创建NSMutableAttributedString对象
let attributedString = NSMutableAttributedString(string: "Hello World!")

// 设置字体和字号
let font = UIFont(name: "Helvetica", size: 16)!
attributedString.addAttribute(.font, value: font, range: NSRange(location: 0, length: attributedString.length))

// 设置字体颜色
let textColor = UIColor.red
attributedString.addAttribute(.foregroundColor, value: textColor, range: NSRange(location: 0, length: attributedString.length))

// 设置背景颜色
let backgroundColor = UIColor.yellow
attributedString.addAttribute(.backgroundColor, value: backgroundColor, range: NSRange(location: 0, length: attributedString.length))

// 添加下划线
attributedString.addAttribute(.underlineStyle, value: NSUnderlineStyle.single.rawValue, range: NSRange(location: 0, length: attributedString.length))

// 添加链接
let linkURL = URL(string: "https://www.example.com")!
attributedString.addAttribute(.link, value: linkURL, range: NSRange(location: 0, length: attributedString.length))

// 在UILabel或UITextView中显示富文本
label.attributedText = attributedString