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Build AttributedString from HTML String content. Fonts can be linked locally.
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| // | |
| // HTMLBuilder.swift | |
| // HTMLBuilder | |
| // | |
| // Created by Lal Krishna on 11/03/22. | |
| // Copyright © 2022 Lal Krishna. All rights reserved. | |
| // | |
| import Foundation | |
| import UIKit | |
| extension HTMLBuilder { | |
| static func `default`() -> Self { | |
| let font = UIFont.appFont(style: .regular, ofSize: 22) | |
| let fontFaces = [ | |
| font.fontName: font.fontName + ".ttf" | |
| ] | |
| let builder = HTMLBuilder(defaultFontName: font.fontName, fontFaces: fontFaces) | |
| return builder | |
| } | |
| } | |
| struct HTMLBuilder { | |
| let css: String | |
| typealias FontName = String | |
| typealias FontFileName = String | |
| /// Key-value pair | |
| /// Example: `[ "Arial-Bold": "Arial_Bold.ttf"` | |
| var fontFaces: [FontName: FontFileName] | |
| private var bodyContent: String = "" | |
| init(defaultFontName: String, fontFaces: [FontName: FontFileName]? = nil, css: String? = nil) { | |
| self.fontFaces = fontFaces ?? [:] | |
| self.css = css ?? Self.defaultCSS(defaultFontName: defaultFontName) | |
| } | |
| private var attributedText: NSAttributedString? { | |
| let htmlContent = html | |
| let htmlData = NSString(string: htmlContent).data(using: String.Encoding.unicode.rawValue) | |
| let options = [NSAttributedString.DocumentReadingOptionKey.documentType: NSAttributedString.DocumentType.html] | |
| let attributedString = try? NSAttributedString(data: htmlData!, options: options, documentAttributes: nil) | |
| return attributedString | |
| } | |
| mutating func buildAttributedString(_ htmlContent: String, color: UIColor? = nil) -> NSAttributedString? { | |
| self.bodyContent = htmlContent | |
| guard let attributed = attributedText else { return nil } | |
| guard let color = color else { return attributed } | |
| let mutable = NSMutableAttributedString(attributedString: attributed) | |
| mutable.addAttributes([.foregroundColor: color], range: .init(location: 0, length: attributed.length)) | |
| return mutable | |
| } | |
| var html: String { | |
| """ | |
| <html> | |
| \(head) | |
| <body> | |
| \(bodyContent) | |
| </body> | |
| </html> | |
| """ | |
| } | |
| var head: String { | |
| """ | |
| </head> | |
| \(style) | |
| </head> | |
| """ | |
| } | |
| var style: String { | |
| """ | |
| <style> | |
| \(fontFacesCSS) | |
| \(css) | |
| </style> | |
| """ | |
| } | |
| private static func defaultCSS(defaultFontName: String) -> String { | |
| """ | |
| body { | |
| font-family: '\(defaultFontName)'; | |
| line-height: 1.6; | |
| } | |
| """ | |
| } | |
| // var css = buildFontFaces() | |
| // let linkCSS = #"<link rel="stylesheet" type="text/css" href="productDescriptionStyle.css">"# | |
| var fontFacesCSS: String { | |
| fontFaces.reduce("") { $0 + "\n" + Self.fontFace(name: $1.key, path: $1.value) } | |
| } | |
| mutating func addFontFace(name: String, path: String) { | |
| fontFaces[name] = path | |
| } | |
| private static func fontFace(name: String, path: String) -> String { | |
| """ | |
| @font-face { | |
| font-family: '\(name)'; | |
| src: local('\(name)'),url('\(path)')'); | |
| } | |
| """ | |
| } | |
| } | |
| // Usage | |
| // HTMLBuilder.default().buildAttributedString(htmlContentString, color: UIColor.red) |
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