how to convert Arabic numbers to English numbers in swift?

in my app, I have 5 uitextfields. My intended users are Arabic speakers so when they use my app, they will either insert number in English or in Arabic.

The app works just fine with English numbers. However, when I run it and insert numbers in Arabic, the app deals with the textfields as if they all were empty and gives the answer as 0

How can I make sure that the textfields are not nill AND a double, whithout ignoring Arabic numbers?

This is the code inside the "calButton" function:

     /*let value1 = Double(income.text ?? "") ?? 0
    let value2 = Double(salaries.text ?? "") ?? 0
    let value3 = Double(tools.text ?? "") ?? 0
    let value4 = Double(maintinance.text ?? "") ?? 0
    let value5 = Double(otherExpenses.text ?? "") ?? 0
    let sum = value1 - ( value2 + value3 + value4 + value5)

    print("result is: \(sum)")*/



    let textFields = [income, salaries, tools, maintinance, otherExpenses]
    var sum = 0.0
    for textField in textFields {
        if let number = Double((textField?.text!)!) { //checks that it is not nil AND a Double
            sum += number
        }
    }

    expensesTotal.text = String(sum)
    // print("result is: \(sum)")

You need to convert the arabic number string to english first and then do the calculation part.

    let numberStr: String = "٨٦٩١٢٨٨١"
    let formatter: NumberFormatter = NumberFormatter()
    formatter.locale = NSLocale(localeIdentifier: "EN") as Locale!
    let final = formatter.number(from: numberStr)
    let doubleNumber = Double(final!)
    print("\(doubleNumber)")

From Any language, To Any Language

You can convert digits from ANY language to ANY other language in a single line code like:

"12345".convertedDigitsToLocale(Locale(identifier: "FA")) /* ۱۲۳۴۵ */

"۱۲۳۴۵".convertedDigitsToLocale(Locale(identifier: "EN")) /* 12345 */

with the following extension:

extension String {
    private static let formatter = NumberFormatter()

    func clippingCharacters(in characterSet: CharacterSet) -> String {
        components(separatedBy: characterSet).joined()
    }

    func convertedDigitsToLocale(_ locale: Locale = .current) -> String {
        let digits = Set(clippingCharacters(in: CharacterSet.decimalDigits.inverted))
        guard !digits.isEmpty else { return self }

        Self.formatter.locale = locale

        let maps: [(original: String, converted: String)] = digits.map {
            let original = String($0)
            let digit = Self.formatter.number(from: original)!
            let localized = Self.formatter.string(from: digit)!
            return (original, localized)
        }

        return maps.reduce(self) { converted, map in
            converted.replacingOccurrences(of: map.original, with: map.converted)
        }
    }
}

The Swift Package

You can find this extension and some more useful extensions with their unit test Here on the github and use them easily as a Swift package.

Swift-5 solution for all non-Latin string occurrences.

extension String {
    var containsNonEnglishNumbers: Bool {
        return !isEmpty && range(of: "[^0-9]", options: .regularExpression) == nil
    }

    var english: String {
        return self.applyingTransform(StringTransform.toLatin, reverse: false) ?? self
    }
}

Usage -

textField.addTarget(self, action: #selector(didChangeText(field:)), for: .editingChanged)

@objc func didChangeText(field: UITextField) {
    if ((field.text?.containsNonEnglishNumbers) != nil) {
        field.text = field.text?.english
    }
}

This will replace any arabic number to english

 func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        if textField.keyboardType == .numberPad && string != "" {
            let numberStr: String = string
            let formatter: NumberFormatter = NumberFormatter()
            formatter.locale = Locale(identifier: "EN")
            if let final = formatter.number(from: numberStr) {
                textField.text =  "\(textField.text ?? "")\(final)"
            }
                return false
        }
        return true
    }

dont forget setting the delegate:

yourTextField.delegat = self