Iphone 在iOS中将HTML转换为NSAttributedString

我正在使用

UIWebView

的一个实例来处理一些文本并正确地为其着色，它以HTML的形式给出结果，但不是在

UIWebView

中显示它，而是使用

Core text

和

nsattributed字符串来显示它

我能够创建并绘制
NSAttributedString
，但我不确定如何将HTML转换并映射到属性字符串

我知道在Mac OS X下，NSAttributedString有一个
initWithHTML:
方法，但这是一个仅适用于Mac的添加，不适用于iOS

我也知道有一个类似的问题，但没有答案，我想我会再试一次，看看是否有人创造了这样做的方法，如果有，他们是否可以分享它。
现在唯一的解决方案是解析HTML，建立一些具有给定点/font/etc属性的节点，然后将它们组合成一个NSAttributed字符串。这是一项大量的工作，但如果做得正确，将来可以重复使用。
Github的Oliver Drobnik正在进行一项工作。它使用NSScanner进行HTML解析。
在iOS 7中，UIKit添加了一种方法，可以使用HTML初始化
NSAttributedString
，例如：

[[NSAttributedString alloc] initWithData:[htmlString dataUsingEncoding:NSUTF8StringEncoding] 
                                 options:@{NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType,
                                           NSCharacterEncodingDocumentAttribute: @(NSUTF8StringEncoding)} 
                      documentAttributes:nil error:nil];

迅速：

let htmlData = NSString(string: details).data(using: String.Encoding.unicode.rawValue)
let options = [NSAttributedString.DocumentReadingOptionKey.documentType:
        NSAttributedString.DocumentType.html]
let attributedString = try? NSMutableAttributedString(data: htmlData ?? Data(),
                                                          options: options,
                                                          documentAttributes: nil)

从HTML创建NSAttributedString必须在主线程上完成！
更新：NSAttributedString HTML呈现取决于引擎盖下的WebKit，必须在主线程上运行，否则偶尔会导致应用程序崩溃

New Relic崩溃日志：


以下是更新的线程安全的Swift 2字符串扩展名：

extension String {
    func attributedStringFromHTML(completionBlock:NSAttributedString? ->()) {
        guard let data = dataUsingEncoding(NSUTF8StringEncoding) else {
            print("Unable to decode data from html string: \(self)")
            return completionBlock(nil)
        }

        let options = [NSDocumentTypeDocumentAttribute : NSHTMLTextDocumentType,
                   NSCharacterEncodingDocumentAttribute: NSNumber(unsignedInteger:NSUTF8StringEncoding)]

        dispatch_async(dispatch_get_main_queue()) {
            if let attributedString = try? NSAttributedString(data: data, options: options, documentAttributes: nil) {
                completionBlock(attributedString)
            } else {
                print("Unable to create attributed string from html string: \(self)")
                completionBlock(nil)
            }
        }
    }
}

用法：

let html = "<center>Here is some <b>HTML</b></center>"
html.attributedStringFromHTML { attString in
    self.bodyLabel.attributedText = attString
}

let html=“这是一些html”
html.attributedStringFromHTML{attString in
self.bodyLabel.AttributeText=attString
}

输出：

上述解决方案是正确的

[[NSAttributedString alloc] initWithData:[htmlString dataUsingEncoding:NSUTF8StringEncoding] 
                                 options:@{NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType,
                                           NSCharacterEncodingDocumentAttribute: @(NSUTF8StringEncoding)} 
                      documentAttributes:nil error:nil];

但如果在ios 8.1、2或3上运行，应用程序wioll将崩溃。

要避免崩溃，您可以做的是：在队列中运行此命令。因此它总是在主线程上。
这是一个用Swift编写的
字符串
扩展，用于返回HTML字符串作为
NSAttributedString

extension String {
    func htmlAttributedString() -> NSAttributedString? {
        guard let data = self.dataUsingEncoding(NSUTF16StringEncoding, allowLossyConversion: false) else { return nil }
        guard let html = try? NSMutableAttributedString(data: data, options: [NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType], documentAttributes: nil) else { return nil }
        return html
    }
}

使用

label.attributedText = "<b>Hello</b> \u{2022} babe".htmlAttributedString()

label.attributeText=“Hello\u{2022}babe”.htmlAttributedString（）

在上面，我特意添加了一个unicode\u2022，以显示它正确呈现unicode

一个小问题是：
NSAttributedString
使用的默认编码是
NSUTF16StringEncoding
（不是UTF8！）。
有用的扩展
受这个线程、一个pod和Erica Sadun在iOS Gourmet Cookbook p.80中的ObjC示例的启发，我在GitHub上编写了一个扩展名
String
和
NSAttributedString
，在HTML纯字符串和NSAttributedString之间来回切换，反之亦然，我发现这很有帮助

签名是（同样，要点中的完整代码，上面的链接）：

Swift 3.0 Xcode 8版本

func htmlAttributedString() -> NSAttributedString? {
    guard let data = self.data(using: String.Encoding.utf16, allowLossyConversion: false) else { return nil }
    guard let html = try? NSMutableAttributedString(data: data, options: [NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType], documentAttributes: nil) else { return nil }
    return html
}

对的解决方案进行了一些修改，并将代码更新为Swift 3：

这段代码现在使用UITextView作为
self
，并且能够继承其原始字体、字体大小和文本颜色

注意：
toHexString（）
是的扩展名

扩展UITextView{
func setAttributedStringFromHTML（htmlCode:String，completionBlock:@escaping（NSAttributedString？）->（））{
让inputText=“\（htmlCode）正文{字体系列：'\（（self.font？.fontName）！）”；字体大小：\（（self.font？.pointSize）！）px；颜色：\（（self.textColor）！.tohextString（）；）
guard let data=inputText.data（使用：String.Encoding.utf16）else{
打印（“无法解码html字符串中的数据：\（self）”）
返回完成块（nil）
}
DispatchQueue.main.async{
如果let attributedString=try？NSAttributedString（数据：数据，选项：[NSDocumentTypeDocumentAttribute:NSHTMLTextDocumentType]，DocumentAttribute:nil）{
self.attributedText=attributedString
completionBlock（attributedString）
}否则{
打印（“无法从html字符串创建属性字符串：\（self）”）
完成块（无）
}
}
}
}

用法示例：

mainTextView.setAttributedStringFromHTML("<i>Hello world!</i>") { _ in }

mainTextView.setAttributedStringFromHTML（“你好，世界！”）{in}

使用NSHTMLTextDocumentType速度慢，而且很难控制样式。我建议你试试我的图书馆，它叫Atributika。它有自己的非常快速的HTML解析器。您还可以拥有任何标记名并为其定义任何样式

例如：

let str = "<strong>Hello</strong> World!".style(tags:
    Style("strong").font(.boldSystemFont(ofSize: 15))).attributedString

label.attributedText = str

let str=“HelloWorld！”。样式（标记：
样式（“强”）.font（.boldSystemFont（大小：15））.attributedString
label.attributeText=str

---

您可以在这里找到它

Swift 3：
试试这个：

及使用:

let str = "<h1>Hello bro</h1><h2>Come On</h2><h3>Go sis</h3><ul><li>ME 1</li><li>ME 2</li></ul> <p>It is me bro , remember please</p>"

self.contentLabel.attributedText = str.htmlAttributedString()

let str=“你好，broCome OnGo sis
我1
我2
是我，兄弟，请记住
”
self.contentLabel.AttributeText=str.htmlAttributedString（）

NSAttribute字符串上的Swift初始值设定项扩展 我倾向于将其作为

NSAttributedString

的扩展，而不是

String

。我尝试将其作为静态扩展和初始值设定项。我更喜欢初始值设定项，这是我在下面包含的

---

Swift 4

internal convenience init?(html: String) {
    guard let data = html.data(using: String.Encoding.utf16, allowLossyConversion: false) else {
        return nil
    }

    guard let attributedString = try?  NSAttributedString(data: data, options: [.documentType: NSAttributedString.DocumentType.html, .characterEncoding: String.Encoding.utf8.rawValue], documentAttributes: nil) else {
        return nil
    }

    self.init(attributedString: attributedString)
}

Swift 3

extension NSAttributedString {

internal convenience init?(html: String) {
    guard let data = html.data(using: String.Encoding.utf16, allowLossyConversion: false) else {
        return nil
    }

    guard let attributedString = try? NSMutableAttributedString(data: data, options: [NSAttributedString.DocumentReadingOptionKey.documentType: NSAttributedString.DocumentType.html], documentAttributes: nil) else {
        return nil
    }

    self.init(attributedString: attributedString)
}
}

示例

let html = "<b>Hello World!</b>"
let attributedString = NSAttributedString(html: html)

UILabel.attributedText = try? NSAttributedString(htmlString: "<strong>Hello</strong> World!")

让html=“你好，世界！”
让attributedString=NSAttributedString（html:html）

Swift 4

internal convenience init?(html: String) {
    guard let data = html.data(using: String.Encoding.utf16, allowLossyConversion: false) else {
        return nil
    }

    guard let attributedString = try?  NSAttributedString(data: data, options: [.documentType: NSAttributedString.DocumentType.html, .characterEncoding: String.Encoding.utf8.rawValue], documentAttributes: nil) else {
        return nil
    }

    self.init(attributedString: attributedString)
}

---

• NSAttributedString便利初始值设定项
• 没有额外的警卫
• 抛出错误

---

用法

let html = "<b>Hello World!</b>"
let attributedString = NSAttributedString(html: html)

UILabel.attributedText = try? NSAttributedString(htmlString: "<strong>Hello</strong> World!")

UILabel.attributedText=try？NSAttributedString（htmlString:你好世界！”）

向字体家族致敬，动态字体我炮制了这个令人憎恶的东西：

extension NSAttributedString
{
    convenience fileprivate init?(html: String, font: UIFont? = Font.dynamic(style: .subheadline))
    {
        guard let data = html.data(using: String.Encoding.utf8, allowLossyConversion: true) else {
        var totalString = html
        /*
         https://stackoverflow.com/questions/32660748/how-to-use-apples-new-san-francisco-font-on-a-webpage
            .AppleSystemUIFont I get in font.familyName does not work
         while -apple-system does:
         */
        var ffamily = "-apple-system"
        if let font = font {
            let lLDBsucks = font.familyName
            if !lLDBsucks.hasPrefix(".appleSystem") {
                ffamily = font.familyName
            }
            totalString = "<style>\nhtml * {font-family: \(ffamily) !important;}\n            </style>\n" + html
        }
        guard let data = totalString.data(using: String.Encoding.utf8, allowLossyConversion: true) else {
            return nil
        }
        assert(Thread.isMainThread)
        guard let attributedText = try?  NSAttributedString(data: data, options: [.documentType: NSAttributedString.DocumentType.html, .characterEncoding: String.Encoding.utf8.rawValue], documentAttributes: nil) else {
            return nil
        }
        let mutable = NSMutableAttributedString(attributedString: attributedText)
        if let font = font {
        do {
            var found = false
            mutable.beginEditing()
            mutable.enumerateAttribute(NSAttributedString.Key.font, in: NSMakeRange(0, attributedText.length), options: NSAttributedString.EnumerationOptions(rawValue: 0)) { (value, range, stop) in
                    if let oldFont = value as? UIFont {
                        let newsize = oldFont.pointSize * 15 * Font.scaleHeruistic / 12
                        let newFont = oldFont.withSize(newsize)
                        mutable.addAttribute(NSAttributedString.Key.font, value: newFont, range: range)
                        found = true
                    }
                }
                if !found {
                    // No font was found - do something else?
                }

            mutable.endEditing()
            
//            mutable.addAttribute(.font, value: font, range: NSRange(location: 0, length: mutable.length))
        }
        self.init(attributedString: mutable)
    }

}

扩展NSAttributedStrin
extension NSAttributedString
{
    convenience fileprivate init?(html: String, font: UIFont? = Font.dynamic(style: .subheadline))
    {
        guard let data = html.data(using: String.Encoding.utf8, allowLossyConversion: true) else {
        var totalString = html
        /*
         https://stackoverflow.com/questions/32660748/how-to-use-apples-new-san-francisco-font-on-a-webpage
            .AppleSystemUIFont I get in font.familyName does not work
         while -apple-system does:
         */
        var ffamily = "-apple-system"
        if let font = font {
            let lLDBsucks = font.familyName
            if !lLDBsucks.hasPrefix(".appleSystem") {
                ffamily = font.familyName
            }
            totalString = "<style>\nhtml * {font-family: \(ffamily) !important;}\n            </style>\n" + html
        }
        guard let data = totalString.data(using: String.Encoding.utf8, allowLossyConversion: true) else {
            return nil
        }
        assert(Thread.isMainThread)
        guard let attributedText = try?  NSAttributedString(data: data, options: [.documentType: NSAttributedString.DocumentType.html, .characterEncoding: String.Encoding.utf8.rawValue], documentAttributes: nil) else {
            return nil
        }
        let mutable = NSMutableAttributedString(attributedString: attributedText)
        if let font = font {
        do {
            var found = false
            mutable.beginEditing()
            mutable.enumerateAttribute(NSAttributedString.Key.font, in: NSMakeRange(0, attributedText.length), options: NSAttributedString.EnumerationOptions(rawValue: 0)) { (value, range, stop) in
                    if let oldFont = value as? UIFont {
                        let newsize = oldFont.pointSize * 15 * Font.scaleHeruistic / 12
                        let newFont = oldFont.withSize(newsize)
                        mutable.addAttribute(NSAttributedString.Key.font, value: newFont, range: range)
                        found = true
                    }
                }
                if !found {
                    // No font was found - do something else?
                }

            mutable.endEditing()
            
//            mutable.addAttribute(.font, value: font, range: NSRange(location: 0, length: mutable.length))
        }
        self.init(attributedString: mutable)
    }

}

extension NSAttributedString {
    internal convenience init?(html: String)                    {
        guard 
            let data = html.data(using: String.Encoding.utf16, allowLossyConversion: false) else { return nil }

        let options : [DocumentReadingOptionKey : Any] = [
            .documentType: NSAttributedString.DocumentType.html,
            .characterEncoding: String.Encoding.utf8.rawValue
        ]

        guard
            let string = try? NSMutableAttributedString(data: data, options: options,
                                                 documentAttributes: nil) else { return nil }

        if #available(iOS 13, *) {
            let colour = [NSAttributedString.Key.foregroundColor: UIColor.label]
            string.addAttributes(colour, range: NSRange(location: 0, length: string.length))
        }

        self.init(attributedString: string)
    }
}

public extension NSAttributedString {
    convenience init?(_ html: String) {
        guard let data = html.data(using: .unicode) else {
                return nil
        }

        try? self.init(data: data, options: [.documentType: NSAttributedString.DocumentType.html], documentAttributes: nil)
    }
}