将 HTML 转换为 Swift 中的纯文本

Question

我正在开发一个简单的 RSS Reader 应用程序作为 Xcode 中的初学者项目。我目前已将其设置为解析提要，放置标题、发布日期、描述和内容并将其显示在 WebView 中。

我最近决定在用于 select post 的 TableView 中显示描述（或内容的截断版本）。但是，这样做时：

cell.textLabel?.text = item.title?.uppercaseString
cell.detailTextLabel?.text = item.itemDescription //.itemDescription is a String

显示 post 的原始 HTML。

我想知道如何将 HTML 转换为仅用于 TableView 的详细 UILabel 的纯文本。

谢谢！

Answer 1

请使用此代码测试 detailTextLabel：

var attrStr = NSAttributedString(
        data: item.itemDescription.dataUsingEncoding(NSUnicodeStringEncoding, allowLossyConversion: true),
        options: [ NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType],
        documentAttributes: nil,
        error: nil)
cell.detailTextLabel?.text = attrStr

Answer 2

您可以添加此扩展程序以将您的 html 代码转换为常规字符串：

edit/update:

Discussion The HTML importer should not be called from a background thread (that is, the options dictionary includes documentType with a value of html). It will try to synchronize with the main thread, fail, and time out. Calling it from the main thread works (but can still time out if the HTML contains references to external resources, which should be avoided at all costs). The HTML import mechanism is meant for implementing something like markdown (that is, text styles, colors, and so on), not for general HTML import.

Xcode 11.4 • Swift 5.2

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

extension StringProtocol {
    var html2AttributedString: NSAttributedString? {
        Data(utf8).html2AttributedString
    }
    var html2String: String {
        html2AttributedString?.string ?? ""
    }
}

cell.detailTextLabel?.text = item.itemDescription.html2String

Answer 3

这是我建议的答案。如果您想放入内部函数，而不是扩展名。

func decodeString(encodedString:String) -> NSAttributedString?
    {
        let encodedData = encodedString.dataUsingEncoding(NSUTF8StringEncoding)!
        do {
            return try NSAttributedString(data: encodedData, options: [NSDocumentTypeDocumentAttribute:NSHTMLTextDocumentType,NSCharacterEncodingDocumentAttribute:NSUTF8StringEncoding], documentAttributes: nil)
        } catch let error as NSError {
            print(error.localizedDescription)
            return nil
        }
    }

然后调用该函数并将 NSAttributedString 转换为 String

let attributedString = self.decodeString(encodedString)
let message = attributedString.string

Answer 4

我使用了 Danboz 答案，只是将其更改为 return 一个简单的字符串（不是富文本字符串）：

static func htmlToText(encodedString:String) -> String?
{
    let encodedData = encodedString.dataUsingEncoding(NSUTF8StringEncoding)!
    do
    {
        return try NSAttributedString(data: encodedData, options: [NSDocumentTypeDocumentAttribute:NSHTMLTextDocumentType,NSCharacterEncodingDocumentAttribute:NSUTF8StringEncoding], documentAttributes: nil).string
    } catch let error as NSError {
        print(error.localizedDescription)
        return nil
    }
}

对我来说，它就像一个魅力，谢谢 Danboz

Answer 5

Swift 4, Xcode 9

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

extension UILabel {
   func setAttributedHtmlText(_ html: String) {
      if let attributedText = html.attributedHtmlString {
         self.attributedText = attributedText
      } 
   }
}

Answer 6

在 swift3 中尝试这个解决方案

extension String{
    func convertHtml() -> NSAttributedString{
        guard let data = data(using: .utf8) else { return NSAttributedString() }
        do{
            return try NSAttributedString(data: data, options: [NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType, NSCharacterEncodingDocumentAttribute: String.Encoding.utf8.rawValue], documentAttributes: nil)
        }catch{
            return NSAttributedString()
        }
    }
}

使用

self.lblValDesc.attributedText = str_postdescription.convertHtml()

Answer 7

let content = givenString // html included string
let attrStr = try! NSAttributedString(data: content.data(using: String.Encoding.unicode, allowLossyConversion: true)!,options: [ NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType],documentAttributes: nil)
self.labelName.attributedText = attrStr

Answer 8

Swift4.0 扩展

 extension String {
    var html2AttributedString: String? {
    guard let data = data(using: .utf8) else { return nil }
    do {
        return try NSAttributedString(data: data, options: [.documentType: NSAttributedString.DocumentType.html, .characterEncoding: String.Encoding.utf8.rawValue], documentAttributes: nil).string

    } catch let error as NSError {
        print(error.localizedDescription)
        return  nil
    }
  }
}

将 HTML 转换为 Swift 中的纯文本

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