Format currency in textfield in Swift on input

Question

I am trying to format currency input in a textfield in Swift as the user inputs it.

So far, I can only format it successfully when the user finishes inputting:

Answer 1

For Swift 3.0

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {

        // Construct the text that will be in the field if this change is accepted

        switch string {
        case "0","1","2","3","4","5","6","7","8","9":
            currentString += string
            formatCurrency(currentString)
        default:
            if string.characters.count == 0 && currentString.characters.count != 0 {
                currentString = String(currentString.characters.dropLast())
                formatCurrency(currentString)
            }
        }
        return false    }

    func formatCurrency(_ string: String) {
        print("format \(string)")
        let formatter = NumberFormatter()
        formatter.numberStyle = .currency
        formatter.locale = findLocaleByCurrencyCode("NGN")
        let numberFromField = (NSString(string: currentString).doubleValue)/100
        let temp = formatter.string(from: NSNumber(value: numberFromField))
        self.amountTextField.text = String(describing: temp!.characters.dropFirst())
    }

func findLocaleByCurrencyCode(_ currencyCode: String) -> Locale? {

    let locales = Locale.availableIdentifiers 
    var locale: Locale?     
    for   localeId in locales {     
      locale = Locale(identifier: localeId)     
      if let code = (locale! as NSLocale).object(forKey: NSLocale.Key.currencyCode) as? String { 
        if code == currencyCode {
                return locale       
        }   
    } 
}    
return locale }

Answer 2

this works for me using NSNumberFormatter...

func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool {

    // Construct the text that will be in the field if this change is accepted
    var oldText = textField.text as NSString
    var newText = oldText.stringByReplacingCharactersInRange(range, withString: string) as NSString!
    var newTextString = String(newText)

    let digits = NSCharacterSet.decimalDigitCharacterSet()
    var digitText = ""
    for c in newTextString.unicodeScalars {
        if digits.longCharacterIsMember(c.value) {
            digitText.append(c)
        }
    }

    let formatter = NSNumberFormatter()
    formatter.numberStyle = NSNumberFormatterStyle.CurrencyStyle
    formatter.locale = NSLocale(localeIdentifier: "en_US")
    var numberFromField = (NSString(string: digitText).doubleValue)/100
    newText = formatter.stringFromNumber(numberFromField)

    textField.text = newText

    return false
}

Answer 3

I worked out a normal currency format ( eg 1 is as $1.00, 88885 is as $8,8885.00 and 7555.8569 as $7,555.86.

@IBAction func lostpropertyclicked(sender: AnyObject) {
    var currentString = ""
    currentString = amountTF.text
    formatCurrency(string: currentString)
}

func formatCurrency(#string: String) {
    println("format \(string)")
    let formatter = NSNumberFormatter()
    formatter.numberStyle = NSNumberFormatterStyle.CurrencyStyle
    formatter.locale = NSLocale(localeIdentifier: "en_US")
    var numberFromField = (NSString(string: currentString).doubleValue)
    currentString = formatter.stringFromNumber(numberFromField)!
    println(currentString )
}

Answer 4

Based on @Robert answer. Updated for Swift 2.0

//Textfield delegates
func textField(textField: UITextField, shouldChangeCharactersInRange range: NSRange, replacementString string: String) -> Bool { // return NO to not change text

    switch string {
    case "0","1","2","3","4","5","6","7","8","9":
        currentString += string
        formatCurrency(currentString)
    default:
        if string.characters.count == 0 && currentString.characters.count != 0 {
            currentString = String(currentString.characters.dropLast())
            formatCurrency(currentString)
        }
    }
    return false
}

func formatCurrency(string: String) {
    print("format \(string)")
    let formatter = NSNumberFormatter()
    formatter.numberStyle = NSNumberFormatterStyle.CurrencyStyle
    formatter.locale = NSLocale(localeIdentifier: "en_US")
    let numberFromField = (NSString(string: currentString).doubleValue)/100
    self.amountField.text = formatter.stringFromNumber(numberFromField)
    print(self.amountField.text )
}

Answer 5

This worked for me: Naming of the variables need to be improved though. Multiplying by 10 was easy but figuring out how to divide by 10 and round down was tricky with the pointers.

    let numberFormatter = NumberFormatter()
    numberFormatter.numberStyle = .currency


    func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    if textField == amountTextField {
        guard let text = textField.text else {return true}

        let oldDigits = numberFormatter.number(from: text) ?? 0
        var digits = oldDigits.decimalValue

        if let digit = Decimal(string: string) {
            let newDigits: Decimal = digit / 100

            digits *= 10
            digits += newDigits
        }
        if range.length == 1 {
            digits /= 10
            var result = Decimal(integerLiteral: 0)
            NSDecimalRound(&result, &digits, 2, Decimal.RoundingMode.down)
            digits = result
        }

        textField.text = NumberFormatter.localizedString(from: digits as NSDecimalNumber, number: .currency)
        return false
    } else {
        return true
    }
}

Answer 6

Swift 5

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool { // return NO to not change text

    switch string {
    case "0","1","2","3","4","5","6","7","8","9":
        currentString += string
        formatCurrency(string: currentString)
    default:
        if string.count == 0 && currentString.count != 0 {
            currentString = String(currentString.dropLast())
            formatCurrency(string: currentString)
        }
    }
    return false
}

func formatCurrency(string: String) {
    print("format \(string)")
    let formatter = NumberFormatter()
    formatter.numberStyle = NumberFormatter.Style.currency
    formatter.locale = NSLocale(localeIdentifier: "en_US") as Locale
    let numberFromField = (NSString(string: currentString).doubleValue)/100
    //replace billTextField with your text field name
    self.billTextField.text = formatter.string(from: NSNumber(value: numberFromField))
    print(self.billTextField.text ?? "" )
}