CodeseniorSoftware Tutorials

Flutter TextFormField Phone Number Formatter

class PhoneNumberFormatter extends TextInputFormatter {
  PhoneNumberFormatter();

  @override
  TextEditingValue formatEditUpdate(
    TextEditingValue oldValue,
    TextEditingValue newValue,
  ) {
    
    if (!oldValue.text.contains("(") &&
        oldValue.text.length >= 10 &&
        newValue.text.length != oldValue.text.length) {
      return TextEditingValue(
        text: "",
        selection: TextSelection.collapsed(offset: 0),
      );
    }

    if(oldValue.text.length>newValue.text.length){
      return TextEditingValue(
        text: newValue.text.toString(),
        selection: TextSelection.collapsed(offset: newValue.text.length),
      );
    }

    var newText = newValue.text;
    if (newText.length == 1) newText ="(" + newText;
    if (newText.length == 4) newText = newText + ") ";
    if (newText.length == 9) newText = newText + " ";

    return TextEditingValue(
      text: newText.toString(),
      selection: TextSelection.collapsed(offset: newText.length),
    );
  }
}

Usage:

TextFormField(inputFormatters: [PhoneNumberFormatter()])