NSAttributedString from HTML: Add different font sizes for title and description https://stackoverflow.com/questions/56404650

Playground.swift

import UIKit
import PlaygroundSupport

extension UIFont {
    func cssStyle(selector: String, otherStyles styles: String = "") -> String {
        return "\(selector){font-family:\(fontName);font-size:\(Int(pointSize));\(styles)}"
    }
}

let text = "<span class=heading>Stackoverflow</span> is launched in 2008, it currently has 231,083 Swift questions out of 52,499,188 total."
let textView = UITextView(frame: CGRect(x: 0, y: 0, width: 320, height: 320))

let headerStyle = UIFont(name: "ArialRoundedMTBold", size: 30)!.cssStyle(selector: ".heading", otherStyles: "color:#000")
let commonStyle = UIFont(name: "ArialMT", size: 22)!.cssStyle(selector: "*", otherStyles: "color:#666")

let htmlData = Data("<style>\(commonStyle)\(headerStyle)</style>\(text)".utf8)
textView.attributedText = try? NSAttributedString(data: htmlData, options: [
    .documentType: NSAttributedString.DocumentType.html,
    .characterEncoding: String.Encoding.utf8.rawValue
], documentAttributes: nil)

PlaygroundPage.current.liveView = textView