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

Set your controller as the delegate for the text field and check if the proposed string satisfy your requirements:

override func viewDidLoad() {
    super.viewDidLoad()
    textField.delegate = self
    textField.keyboardType = .decimalPad
}

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    guard 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 numberOfDots = newText.components(separatedBy: ".").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
}

Answer 2

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
            let dotString = "."

            if let text = textField.text {
                let isDeleteKey = string.isEmpty

                if !isDeleteKey {
                    if text.contains(dotString) {
                        if text.components(separatedBy: dotString)[1].count == 2 {

                                    return false

                        }

                    }

                }
            }
            return true
         }

Answer 3

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
  }

Answer 4

Guys, here's the solution:

 func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
        let dotString = "."

        if let text = textField.text {
            let isDeleteKey = string.isEmpty

            if !isDeleteKey {
                if text.contains(dotString) {
                    if text.components(separatedBy: dotString)[1].count == 2 {

                                return false

                    }

                }

            }
        }
  }

Answer 5

Swift 5. Adding to Enrique's answer (based on Code Different baseline), I found the need to allow the Delete key to operate anywhere on the line along with a sign (+ or -) or decimal point at the beginning of the input line.

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    // Limit number fields to +/- Real #s: sign as first character, one decimal separator, one decimal place after separator
    if string.isEmpty { return true }   // Allow delete key anywhere!
    guard let oldText = textField.text, let rng = Range(range, in: oldText) else {
        return true
    }
    let newText = oldText.replacingCharacters(in: rng, with: string)

    let isNumeric = newText.isEmpty || (Double(newText) != nil)

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

    let numberOfDecimalDigits: Int
    if let dotIndex = newText.firstIndex(of: ".") {
        numberOfDecimalDigits = newText.distance(from: dotIndex, to: newText.endIndex) - 1
    } else {
        numberOfDecimalDigits = 0
    }
    if newText.count == 1 && !isNumeric {   // Allow first character to be a sign or decimal point
        return CharacterSet(charactersIn: "+-" + decimalPoint).isSuperset(of: CharacterSet(charactersIn: string))
    }
    return isNumeric && numberOfDots <= 1 && numberOfDecimalDigits <= 1
}

Answer 6

Only Two decimal point allow and only one "." allow

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

                    let text: NSString = textField.text! as NSString
                    let resultString = text.replacingCharacters(in: range, with: string)


        //Check the specific textField 
         if textField == costTextField {
             let textArray = resultString.components(separatedBy: ".")
             if textArray.count > 2 { //Allow only one "."
                return false
             }
           if textArray.count == 2 {
              let lastString = textArray.last
             if lastString!.count > 2 { //Check number of decimal places 
                   return false
               }
            }
          }
           return true
       }