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Swift-Change the font to an HTML string that has its own styles

I dynamically get an HTML string from the Wordpress API and parse it into an Attributed String to show it in my application. Since the line has its own styles, it shows different fonts and sizes, which affects our design options.

What I want to do is change the font and its size to the entire sent string.

I tried to do this in the attribute string parameters, but does nothing:

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

Does anyone have any ideas on how to achieve this?

PS I know that I could add a CSS tag to the beginning or end of a line, but will this override other styles? Also, if this is a feasible solution, could you please provide a sample of how to do this?

+7
6

setAttributes reset HTML. , :

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)
    }
}

:

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
+9

, , NSAttributedString NSMutableAttributedString.

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

addAttributes, , , , , .

, , , , . , :

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
}

, , , . HTML- , :

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)

, NSMutableAttributedString, . , , :

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)
        }
    }

:

enter image description here

, , .

+16

Swift 4

  • NSAttributedString
  • (HTML-) UIFont
  • HTML UIFont, @see useDocumentFontSize
  • HTML NSAttributedString , , @see guard
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)
    }

}

-1 ( )

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

-2 (NSMutableAttributedString)

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

-3 ( HTML NSAttributedString)

let attr = try? NSAttributedString(htmlString: "<strong>Hello</strong> World!")
+12

Swift 3 version of my previous (Swift 4) solution

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)
    }

}
+5
source 
let font = "<font face='Montserrat-Regular' size='13' color= 'black'>%@"
let html = String(format: font, yourhtmlstring)
webView.loadHTMLString(html, baseURL: nil)
0
source 
let font = UIFont(name: fontName, size: fontSize)
textAttributes[NSFontAttributeName] = font
self.attributedText = NSAttributedString(string: self.text, attributes: textAttributes)
-1
source

Source: https://habr.com/ru/post/1665439/

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