无法将NSAttributedString.DocumentAttributeKey类型的值转换为.DocumentReadingOptionKey

问题描述

我在互联网上找到了这个字符串扩展，允许我将html代码转换为属性字符串：

I found this string extension somewhere on the internet that allows me to turn html code into an attributed string:

func html2AttributedString() -> NSAttributedString {
    return try! NSAttributedString(data: self.data(using: String.Encoding.unicode, allowLossyConversion: true)!, options: [NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType], documentAttributes: nil)
}

它在Swift 3中运行良好，但是对于Swift 4，Xcode抱怨：

It worked fine in Swift 3, but with Swift 4, Xcode complains:

如何做我解决了这个问题？

How do I fix this?

推荐答案

你需要传递一个可用的NSAttributedString 选项：

You need to pass one of the available NSAttributedString DocumentType options:

static let html: NSAttributedString.DocumentType

---

---

static let plain: NSAttributedString.DocumentType

---

---

static let rtf: NSAttributedString.DocumentType

---

---

static let rtfd: NSAttributedString.DocumentType

---

在这种情况下，您需要传递第一个（html） NSAttributedString.DocumentType.html

所以扩展到Swift 4应该如下所示：

So the extension updated to Swift 4 should look like this:

extension String {
    var html2AttributedString: NSAttributedString? {
        do {
            return try NSAttributedString(data: Data(utf8),
                                          options: [.documentType: NSAttributedString.DocumentType.html,
                                                    .characterEncoding: String.Encoding.utf8.rawValue],
                                          documentAttributes: nil)
        } catch {
            print("error: ", error)
            return nil
        }
    }
    var html2String: String {
        return html2AttributedString?.string ?? ""
    }
}

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