How to limit the textfield entry to 2 decimal places in swift 4?

Question

I have a textfield and I want to limit the entry to max 2 decimal places.

number like 12.34 is allowed but not 12.345

How do I do it?

Answer 1

Following the Code Different's answer, I've improved the code to support a different Locale and different UITextFields in the same class.

  func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    guard textField.keyboardType == .decimalPad, let oldText = textField.text, let r = Range(range, in: oldText) else {
        return true
    }

    let newText = oldText.replacingCharacters(in: r, with: string)
    let isNumeric = newText.isEmpty || (Double(newText) != nil)

    let formatter = NumberFormatter()
    formatter.locale = Locale.current
    let decimalPoint = formatter.decimalSeparator ?? "."
    let numberOfDots = newText.components(separatedBy: decimalPoint).count - 1

    let numberOfDecimalDigits: Int
    if let dotIndex = newText.index(of: ".") {
        numberOfDecimalDigits = newText.distance(from: dotIndex, to: newText.endIndex) - 1
    } else {
        numberOfDecimalDigits = 0
    }
    return isNumeric && numberOfDots <= 1 && numberOfDecimalDigits <= 2
  }