как получить доступ к странице 404 с помощью .htaccess

SWIFT 4

extension String {

mutating func toHtmlEncodedString() {
    guard let encodedData = self.data(using: .utf8) else {
        return
    }

    let attributedOptions: [NSAttributedString.DocumentReadingOptionKey : Any] = [
        NSAttributedString.DocumentReadingOptionKey(rawValue: NSAttributedString.DocumentAttributeKey.documentType.rawValue): NSAttributedString.DocumentType.html,
        NSAttributedString.DocumentReadingOptionKey(rawValue: NSAttributedString.DocumentAttributeKey.characterEncoding.rawValue): String.Encoding.utf8.rawValue
    ]

    do {
        let attributedString = try NSAttributedString(data: encodedData, options: attributedOptions, documentAttributes: nil)
        self = attributedString.string
    } catch {
        print("Error: \(error)")

    }
}