How do you dynamically format a number to have commas in a UITextField entry?

Question

I want to have commas dynamically added to my numeric UITextField entry while the user is typing.

For example: 123,456 and 12,345,678

Answer 1

I have another one. Fix some bugs with local configuration and zero after decimal point

func textField(_ textField: UITextField, shouldChangeCharactersIn range: NSRange, replacementString string: String) -> Bool {
    
    let point = Locale.current.decimalSeparator!
    let decSep = Locale.current.groupingSeparator!
    
    
    let text = textField.text!
    let textRange = Range(range, in: text)!
    
    var fractionLength = 0
    var isRangeUpperPoint = false
    
    if let startPoint = text.lastIndex(of: point.first!) {
        let end = text.endIndex
        let str = String(text[startPoint..= startPoint
    }
    
    if  fractionLength == 3 && string != "" && isRangeUpperPoint {
        return false
    }
    
    let r = (textField.text! as NSString).range(of: point).location < range.location
    if (string == "0" || string == "") && r {
        return true
    }
    
    // First check whether the replacement string's numeric...
    let cs = NSCharacterSet(charactersIn: "0123456789\(point)").inverted
    let filtered = string.components(separatedBy: cs)
    let component = filtered.joined(separator: "")
    let isNumeric = string == component
    
    
    if isNumeric {
        let formatter = NumberFormatter()
        formatter.numberStyle = .decimal
        formatter.maximumFractionDigits = 2
        // Combine the new text with the old; then remove any
        // commas from the textField before formatting
        
        
        let newString = text.replacingCharacters(in: textRange,  with: string)
        
        
        let numberWithOutCommas = newString.replacingOccurrences(of: decSep, with: "")
        let number = formatter.number(from: numberWithOutCommas)
        if number != nil {
            var formattedString = formatter.string(from: number!)
            // If the last entry was a decimal or a zero after a decimal,
            // re-add it here because the formatter will naturally remove
            // it.
            if string == point && range.location == textField.text?.count {
                formattedString = formattedString?.appending(point)
            }
            textField.text = formattedString
        } else {
            textField.text = nil
        }
    }
    
    
    
   return false
    
}