Question

我正在从Wordpress API获取HTML字符串并将其解析为Attributed String以在我的应用中显示它。由于字符串有自己的样式，它会显示不同的字体和大小，这会影响我们的设计选择。

我想要做的是在整个属性字符串上更改字体及其大小。

我尝试在属性字符串的选项中这样做，但它没有做任何事情：

let attributedT = try! NSAttributedString(
            data: nContent!.decodeHTML().data(using: String.Encoding.unicode, allowLossyConversion: true)!,
            options: [ NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType, NSFontAttributeName: UIFont(name: "Helvetica", size: 16.0)!],
            documentAttributes: nil)
        contentLbl.attributedText = attributedT

有没有人对如何实现这一点有任何想法？

P.S。我知道我可以在字符串的开头或结尾添加一个CSS标签，但这会覆盖其中的其他样式吗？另外，如果这是一个有效的解决方案，你能否提供一个如何做的样本？

Answer 1

基本上，您要做的是将NSAttributedString转换为NSMutableAttributedString。

let attributedT = // ... attributed string
let mutableT = NSMutableAttributedString(attributedString:attributedT)

现在，您可以调用addAttributes将属性（例如不同的字体）应用于任何所需的范围，例如整个事物。

然而，不幸的是，没有象征性特征的字体（如斜体）是具有该符号特征的字体的不同字体。因此，您需要一个从字体复制现有符号特征并将其应用于另一种字体的实用程序：

func applyTraitsFromFont(_ f1: UIFont, to f2: UIFont) -> UIFont? {
    let t = f1.fontDescriptor.symbolicTraits
    if let fd = f2.fontDescriptor.withSymbolicTraits(t) {
        return UIFont.init(descriptor: fd, size: 0)
    }
    return nil
}

好的，所以，有了这个实用程序，让我们试一试。我将从一些简单的HTML开始并将其转换为属性字符串，就像您正在做的那样：

let html = "<p>Hello <i>world</i>, hello</p>"
let data = html.data(using: .utf8)!
let att = try! NSAttributedString.init(
    data: data, options: [NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType],
    documentAttributes: nil)
let matt = NSMutableAttributedString(attributedString:att)

正如您所见，我已经转换为NSMutableAttributedString，正如我所建议的那样。现在，我将通过样式运行循环，在使用我的实用程序应用现有特征时改变为不同的字体：

matt.enumerateAttribute(
    NSFontAttributeName,
    in:NSMakeRange(0,matt.length),
    options:.longestEffectiveRangeNotRequired) { value, range, stop in
        let f1 = value as! UIFont
        let f2 = UIFont(name:"Georgia", size:20)!
        if let f3 = applyTraitsFromFont(f1, to:f2) {
            matt.addAttribute(
                NSFontAttributeName, value:f3, range:range)
        }
    }

结果如下：

显然，根据您的设计需求，您可以调整此过程，使其更加复杂。

Answer 2

Swift 4 解决方案

NSAttributedString扩展程序
枚举属性字符串（HTML文档）字体属性，并替换为提供的UIFont
保留原始HTML字体大小，或使用提供的UIFont，@ see useDocumentFontSize参数
此方法可以简单地将HTML转换为NSAttributedString，而不会过度使用字体进行操作，只需跳过字体参数@see guard语句

extension NSAttributedString {

    convenience init(htmlString html: String, font: UIFont? = nil, useDocumentFontSize: Bool = true) throws {
        let options: [NSAttributedString.DocumentReadingOptionKey : Any] = [
            .documentType: NSAttributedString.DocumentType.html,
            .characterEncoding: String.Encoding.utf8.rawValue
        ]

        let data = html.data(using: .utf8, allowLossyConversion: true)
        guard (data != nil), let fontFamily = font?.familyName, let attr = try? NSMutableAttributedString(data: data!, options: options, documentAttributes: nil) else {
            try self.init(data: data ?? Data(html.utf8), options: options, documentAttributes: nil)
            return
        }

        let fontSize: CGFloat? = useDocumentFontSize ? nil : font!.pointSize
        let range = NSRange(location: 0, length: attr.length)
        attr.enumerateAttribute(.font, in: range, options: .longestEffectiveRangeNotRequired) { attrib, range, _ in
            if let htmlFont = attrib as? UIFont {
                let traits = htmlFont.fontDescriptor.symbolicTraits
                var descrip = htmlFont.fontDescriptor.withFamily(fontFamily)

                if (traits.rawValue & UIFontDescriptorSymbolicTraits.traitBold.rawValue) != 0 {
                    descrip = descrip.withSymbolicTraits(.traitBold)!
                }

                if (traits.rawValue & UIFontDescriptorSymbolicTraits.traitItalic.rawValue) != 0 {
                    descrip = descrip.withSymbolicTraits(.traitItalic)!
                }

                attr.addAttribute(.font, value: UIFont(descriptor: descrip, size: fontSize ?? htmlFont.pointSize), range: range)
            }
        }

        self.init(attributedString: attr)
    }

}

用法-1（替换字体）

let attr = try? NSAttributedString(htmlString: "<strong>Hello</strong> World!", font: UIFont.systemFont(ofSize: 34, weight: .thin))

用法2（NSMutableAttributedString示例）

let attr = try! NSMutableAttributedString(htmlString: "<strong>Hello</strong> World!", font: UIFont.systemFont(ofSize: 34, weight: .thin))
attr.append(NSAttributedString(string: " MINIMIZE", attributes: [.link: "@m"]))

用法-3（仅将HTML转换为NSAttributedString）

let attr = try? NSAttributedString(htmlString: "<strong>Hello</strong> World!")

Answer 3

setAttributes将重置HTML中的所有属性。我写了一个扩展方法来避免这种情况：

Swift 4

public convenience init?(HTMLString html: String, font: UIFont? = nil) throws {
    let options : [NSAttributedString.DocumentReadingOptionKey : Any] =
        [NSAttributedString.DocumentReadingOptionKey.documentType: NSAttributedString.DocumentType.html,
         NSAttributedString.DocumentReadingOptionKey.characterEncoding: String.Encoding.utf8.rawValue]

    guard let data = html.data(using: .utf8, allowLossyConversion: true) else {
        throw NSError(domain: "Parse Error", code: 0, userInfo: nil)
    }

    if let font = font {
        guard let attr = try? NSMutableAttributedString(data: data, options: options, documentAttributes: nil) else {
            throw NSError(domain: "Parse Error", code: 0, userInfo: nil)
        }
        var attrs = attr.attributes(at: 0, effectiveRange: nil)
        attrs[NSAttributedStringKey.font] = font
        attr.setAttributes(attrs, range: NSRange(location: 0, length: attr.length))
        self.init(attributedString: attr)
    } else {
        try? self.init(data: data, options: options, documentAttributes: nil)
    }
}

测试样本：

let html = "<html><body><h1 style=\"color:red;\">html text here</h1></body></html>"
let font = UIFont.systemFont(ofSize: 16)

var attr = try NSMutableAttributedString(HTMLString: html, font: nil)
var attrs = attr?.attributes(at: 0, effectiveRange: nil)
attrs?[NSAttributedStringKey.font] as? UIFont
// print: <UICTFont: 0x7ff19fd0a530> font-family: "TimesNewRomanPS-BoldMT"; font-weight: bold; font-style: normal; font-size: 24.00pt

attr = try NSMutableAttributedString(HTMLString: html, font: font)
attrs = attr?.attributes(at: 0, effectiveRange: nil)
attrs?[NSAttributedStringKey.font] as? UIFont
// print: <UICTFont: 0x7f8c0cc04620> font-family: ".SFUIText"; font-weight: normal; font-style: normal; font-size: 16.00pt

Answer 4

我以前的（Swift 4）解决方案的Swift 3 版本

extension NSAttributedString {

    convenience init(htmlString html: String, font: UIFont? = nil, useDocumentFontSize: Bool = true) throws {
        let options: [String : Any] = [
            NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType,
            NSCharacterEncodingDocumentAttribute: String.Encoding.utf8.rawValue
        ]

        let data = html.data(using: .utf8, allowLossyConversion: true)
        guard (data != nil), let fontFamily = font?.familyName, let attr = try? NSMutableAttributedString(data: data!, options: options, documentAttributes: nil) else {
            try self.init(data: data ?? Data(html.utf8), options: options, documentAttributes: nil)
            return
        }

        let fontSize: CGFloat? = useDocumentFontSize ? nil : font!.pointSize
        let range = NSRange(location: 0, length: attr.length)
        attr.enumerateAttribute(NSFontAttributeName, in: range, options: .longestEffectiveRangeNotRequired) { attrib, range, _ in
            if let htmlFont = attrib as? UIFont {
                let traits = htmlFont.fontDescriptor.symbolicTraits
                var descrip = htmlFont.fontDescriptor.withFamily(fontFamily)

                if (traits.rawValue & UIFontDescriptorSymbolicTraits.traitBold.rawValue) != 0 {
                    descrip = descrip.withSymbolicTraits(.traitBold)!
                }

                if (traits.rawValue & UIFontDescriptorSymbolicTraits.traitItalic.rawValue) != 0 {
                    descrip = descrip.withSymbolicTraits(.traitItalic)!
                }

                attr.addAttribute(NSFontAttributeName, value: UIFont(descriptor: descrip, size: fontSize ?? htmlFont.pointSize), range: range)
            }
        }

        self.init(attributedString: attr)
    }

}

Answer 5

let font = "<font face='Montserrat-Regular' size='13' color= 'black'>%@"
let html = String(format: font, yourhtmlstring)
webView.loadHTMLString(html, baseURL: nil)

Answer 6

只是想感谢@AamirR 的回应，并警告其他未来的用户关于代码的一个小错误。

如果您使用它，您可能会遇到粗体和斜体字符串的问题，其中最后只使用了其中一个特征。这是修复了该错误的相同代码，希望对您有所帮助：

extension NSAttributedString {

convenience init(htmlString html: String, font: UIFont? = nil, useDocumentFontSize: Bool = true) throws {
    let options: [String : Any] = [
        NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType,
        NSCharacterEncodingDocumentAttribute: String.Encoding.utf8.rawValue
    ]

    let data = html.data(using: .utf8, allowLossyConversion: true)
    guard (data != nil), let fontFamily = font?.familyName, let attr = try? NSMutableAttributedString(data: data!, options: options, documentAttributes: nil) else {
        try self.init(data: data ?? Data(html.utf8), options: options, documentAttributes: nil)
        return
    }

    let fontSize: CGFloat? = useDocumentFontSize ? nil : font!.pointSize
    let range = NSRange(location: 0, length: attr.length)
    attr.enumerateAttribute(NSFontAttributeName, in: range, options: .longestEffectiveRangeNotRequired) { attrib, range, _ in
        if let htmlFont = attrib as? UIFont {
            var traits = htmlFont.fontDescriptor.symbolicTraits
            var descrip = htmlFont.fontDescriptor.withFamily(fontFamily)

            if (traits.rawValue & UIFontDescriptorSymbolicTraits.traitBold.rawValue) != 0 {
                traits = traits.union(.traitBold)
            }

            if (traits.rawValue & UIFontDescriptorSymbolicTraits.traitItalic.rawValue) != 0 {
                traits = traits.union(.traitItalic)
            }

            descrip = descrip.withSymbolicTraits(traits)!
            attr.addAttribute(NSFontAttributeName, value: UIFont(descriptor: descrip, size: fontSize ?? htmlFont.pointSize), range: range)
        }
    }

    self.init(attributedString: attr)
  }
}

Answer 7

let font = UIFont(name: fontName, size: fontSize)
textAttributes[NSFontAttributeName] = font
self.attributedText = NSAttributedString(string: self.text, attributes: textAttributes)

Swift-更改具有自己样式

7 个答案: