您需要传递可用的NSAttributedStringDocumentType选项之一:
超文本标记语言(HTML)文档。
static let html: NSAttributedString.DocumentType
纯文本文档。
static let plain: NSAttributedString.DocumentType
富文本格式的文档。
static let rtf: NSAttributedString.DocumentType
带附件文档的RTF格式。
static let rtfd: NSAttributedString.DocumentType
在这种情况下,您将需要通过第一个(html) NSAttributedString.DocumentType.html
因此,为Swift 4 的扩展应如下所示:
extension NSAttributedString {
convenience init(data: Data, documentType: DocumentType, encoding: String.Encoding = .utf8) throws {
try self.init(data: data,
options: [.documentType: documentType,
.characterEncoding: encoding.rawValue],
documentAttributes: nil)
}
convenience init(html data: Data) throws {
try self.init(data: data, documentType: .html)
}
convenience init(txt data: Data) throws {
try self.init(data: data, documentType: .plain)
}
convenience init(rtf data: Data) throws {
try self.init(data: data, documentType: .rtf)
}
convenience init(rtfd data: Data) throws {
try self.init(data: data, documentType: .rtfd)
}
}
extension StringProtocol {
var data: Data { return Data(utf8) }
var htmlToAttributedString: NSAttributedString? {
do {
return try .init(html: data)
} catch {
print("html error:", error)
return nil
}
}
var htmlDataToString: String? {
return htmlToAttributedString?.string
}
}
extension Data {
var htmlToAttributedString: NSAttributedString? {
do {
return try .init(html: self)
} catch {
print("html error:", error)
return nil
}
}
}
游乐场测试
let htmlString = "<style type=\"text/css\">#red{color:#F00}#green{color:#0F0}#blue{color: #00F; font-weight: Bold; font-size: 32}</style><span id=\"red\" >Red</span><span id=\"green\" > Green </span><span id=\"blue\">Blue</span>"
let htmlData = Data(htmlString.utf8)
htmlString.htmlToAttributedString
htmlData.htmlToAttributedString
讨论不应从后台线程调用HTML导入器(即,选项字典包含值为html的documentType)。它将尝试与主线程同步,失败并超时。从主线程调用它是可行的(但如果HTML包含对外部资源的引用,仍可能会超时,应该不惜一切代价避免这样做)。HTML导入机制用于实现诸如markdown之类的东西(即,文本样式,颜色等),而不是用于常规HTML导入。