A swift string extension to deal with HTML

String+HTML.swift

//
//  String+HTML.swift
//  AttributedString
//
//  Created by Costantino Pistagna on 08/11/2017.
//  Copyright © 2017 sofapps.it All rights reserved.
//

import UIKit
import Foundation

extension UIColor {
    var hexString:String? {
        if let components = self.cgColor.components {
            let r = components[0]
            let g = components[1]
            let b = components[2]
            return  String(format: "%02X%02X%02X", (Int)(r * 255), (Int)(g * 255), (Int)(b * 255))
        }
        return nil
    }
}

extension String {
    var html2Attributed: NSAttributedString? {
        do {
            guard let data = data(using: String.Encoding.utf8) else {
                return nil
            }
            return try NSAttributedString(data: data,
                                          options: [.documentType: NSAttributedString.DocumentType.html,
                                                    .characterEncoding: String.Encoding.utf8.rawValue],
                                          documentAttributes: nil)
        } catch {
            print("error: ", error)
            return nil
        }
    }
    
    var htmlAttributed: (NSAttributedString?, NSDictionary?) {
        do {
            guard let data = data(using: String.Encoding.utf8) else {
                return (nil, nil)
            }

            var dict:NSDictionary?
            dict = NSMutableDictionary()

            return try (NSAttributedString(data: data,
                                          options: [.documentType: NSAttributedString.DocumentType.html,
                                                    .characterEncoding: String.Encoding.utf8.rawValue],
                                          documentAttributes: &dict), dict)
        } catch {
            print("error: ", error)
            return (nil, nil)
        }
    }
    
    func htmlAttributed(using font: UIFont, color: UIColor) -> NSAttributedString? {
        do {
            let htmlCSSString = "<style>" +
                "html *" +
                "{" +
                "font-size: \(font.pointSize)pt !important;" +
                "color: #\(color.hexString!) !important;" +
                "font-family: \(font.familyName), Helvetica !important;" +
                "}</style> \(self)"

            guard let data = htmlCSSString.data(using: String.Encoding.utf8) else {
                return nil
            }

            return try NSAttributedString(data: data,
                                          options: [.documentType: NSAttributedString.DocumentType.html,
                                                    .characterEncoding: String.Encoding.utf8.rawValue],
                                          documentAttributes: nil)
        } catch {
            print("error: ", error)
            return nil
        }
    }

    func htmlAttributed(family: String?, size: CGFloat, color: UIColor) -> NSAttributedString? {
        do {
            let htmlCSSString = "<style>" +
                "html *" +
                "{" +
                "font-size: \(size)pt !important;" +
                "color: #\(color.hexString!) !important;" +
                "font-family: \(family ?? "Helvetica"), Helvetica !important;" +
            "}</style> \(self)"

            guard let data = htmlCSSString.data(using: String.Encoding.utf8) else {
                return nil
            }

            return try NSAttributedString(data: data,
                                          options: [.documentType: NSAttributedString.DocumentType.html,
                                                    .characterEncoding: String.Encoding.utf8.rawValue],
                                          documentAttributes: nil)
        } catch {
            print("error: ", error)
            return nil
        }
    }

}

How can i set the color to Black ,Darktext and DarGray . It throws Crash on hexString Function

func toHexString() -> String
    {
        var r:CGFloat = 0
        var g:CGFloat = 0
        var b:CGFloat = 0
        var a:CGFloat = 0

        getRed(&r, green: &g, blue: &b, alpha: &a)

        let rgb:Int = (Int)(r*255)<<16 | (Int)(g*255)<<8 | (Int)(b*255)<<0

        let hexString = NSString(format:"#%06x", rgb) as String
        return hexString
    }

try this

"font-size: \(font.pointSize)pt !important;" +
"pt" should be replace to "px"