ios - 如何获取存储在 NSTextAttachment 的类型属性中的值？

Question

class AKAttachement: NSTextAttachment{

    var tag:Int!
    var frame: CGRect!
    var type: String!
    var url: URL?

    var completionHandler:((CGRect)->Void)?


    func configure(type:String, tag:Int,frame:CGRect,_url:URL?) {
        self.tag = tag
        self.type = type
        self.url = _url
        self.frame = frame
    }

    override func attachmentBounds(for textContainer: NSTextContainer?, proposedLineFragment lineFrag: CGRect, glyphPosition position: CGPoint, characterIndex charIndex: Int) -> CGRect {
        let superRect = super.attachmentBounds(for: textContainer, proposedLineFragment: lineFrag, glyphPosition: position, characterIndex: charIndex)
        completionHandler?(lineFrag)
        print(lineFrag)

        return superRect

    }
}

我将数据存储在属性中并将其附加到NSAttributedString 当我试图获取AKAttachment子类的对象时NSTextAttachment。

我能够得到对象。但是将type属性设置为 nil。