将NSAttributedString转换为RTFD，然后在Swift中返回

let attributedString = NSAttributedString(string: "Hello, World!", attributes: [NSAttributedString.Key.font: UIFont.systemFont(ofSize: 14)])

guard let rtfdData = try? attributedString.data(from: NSRange(location: 0, length: attributedString.length), documentAttributes: [.documentType: NSAttributedString.DocumentType.rtfd]) else {
    // 转换失败的处理逻辑
    return
}

let fileURL = URL(fileURLWithPath: "path/to/save.rtfd")
do {
    try rtfdData.write(to: fileURL)
    // 保存成功的处理逻辑
} catch {
    // 保存失败的处理逻辑
}