Greek Tax Number Validation in Swift - Έλεγχος ορθότητας ΑΦΜ σε Swift

GreekTaxValidation.swift

//
//  GreekTaxValidation.swift
//
//  Created by Athanasios Papazoglou.
//  
//  Any feedback is appreciated 🤜🤛.
//  Also, you can reach me on Twitter (at)A_Ch_Papazoglou


import Foundation

extension String {
    var isValidGreekTAXNumber: Bool {
        if (self.range(of: "^\\d{9}$", options: .regularExpression) != nil) && (self != "000000000") {
            var sum = 0
            let intArrayTax = self.compactMap({ Int(String($0)) })
            for i in stride(from: 7, through: 0, by: -1) {
                sum += intArrayTax[i] * Int(pow(Double(2), Double(8-i)))
            }
            return sum % 11 % 10 == intArrayTax[8]
        } else {
            return false
        }
    }
}