checkPhoneNumber function
Implementation
String checkPhoneNumber(String _phoneText){
String s = "";
for (int i = 0; i < _phoneText.length; i++) {
int c = _phoneText.codeUnitAt(i);
if ((c == "1".codeUnitAt(0)) || (c == "2".codeUnitAt(0)) || (c == "3".codeUnitAt(0)) ||
(c == "4".codeUnitAt(0)) || (c == "5".codeUnitAt(0)) || (c == "6".codeUnitAt(0)) ||
(c == "7".codeUnitAt(0)) || (c == "8".codeUnitAt(0)) || (c == "9".codeUnitAt(0)) ||
(c == "0".codeUnitAt(0)) || (c == "+".codeUnitAt(0))) {
String h = String.fromCharCode(c);
s = "$s$h";
}
}
return s;
}