包含image的富文本转化为String

1、String转化为富文本（带图片）

//给NSTextAttachment添加一个属性，用于标记富文本转化为String是图片需要转化的文字
class EmojiTextAttachment: NSTextAttachment {
    var emojiTag: String?
}
//生成一个富文本
func makeAttributeString() -> NSAttributedString {
        
        let str = "生成一个富文本，后面随意加一张图片"
        var attrStr = NSMutableAttributedString(string: str)
        let attachment = EmojiTextAttachment()
        attachment.emojiTag = "这里是图片转化成的文字"
        attachment.image = UIImage(named: "插入的图片")
//        attachment.bounds = CGRect() //插入图片的大小
        let att = NSAttributedString(attachment: attachment)
        attrStr.append(att) //直接添加到末尾
//        attrStr.insert(att, at: 3)// 插入
    }

2、富文本转化为String

extension NSAttributedString {
    
    func plainString() -> String {
        var targetString: NSMutableString = NSMutableString(string: self.string)
        //替换下标的偏移量
        var base = 0
        //遍历
        self.enumerateAttribute(NSAttachmentAttributeName, in: NSRange(location: 0, length: self.length), options: .init(rawValue: 0)) { (value, range, stop)  in
            //检查类型是否是自定义NSTextAttachment类
            if let attach = value as? EmojiTextAttachment {
                //替换
                targetString.replaceCharacters(in: NSRange(location: range.location + base, length: range.length), with: attach.emojiTag!)
                //增加偏移量
                base = base + (attach.emojiTag?.count)! - 1
            }
        }
        
        return targetString as String
    }
}

如有错误欢迎指正

方便搜索：
NSAttributedString与String互转
NSAttributedString转String