I have created an UITextField with UIKeyboardTypeNumberPad:

```
tf = [self makeTextField:self.groesse placeholder:@"erforderlich"];
[tf setKeyboardType:UIKeyboardTypeNumberPad];

```

Now, I am trying to mask the entered number, that it will be shown for example like `187 cm` in the UITextField. I have tried it with 

```
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange (NSRange)range replacementString:(NSString *)string {
    if(textField == groesseField_) {
        textField.text = [NSString stringWithFormat:@"%@ cm",string];
        return NO;
    }
    return YES;
}

```

But now, I am only able to input one digit instead of three for the example above.

Can someone help me, what I am doing wrong? - Thanks.