I have tried the code below but that only allows for numbers on the keypad to be inputted. My app requires the keypad to use a period/full stop (for money transactions). The code I tried is:

```
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {

   NSCharacterSet *nonNumberSet = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];

     if ([string rangeOfCharacterFromSet:nonNumberSet].location != NSNotFound)
      {
         return NO;
    }
   return YES;

}

```

Thanks for any help.