Formating decimal on fly on a TextField iOS7 Xcode5 - ios7

Question

I need to achieve this:
When user types (on a textField): 123456
the field will show 123,456
I have the code below, but, for some reason I can figure it out when I type "5" the whole field is reseted to 1.
-(BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
NSString *textt = [textField.text stringByReplacingCharactersInRange:range withString:string];
NSNumberFormatter *formatter = [[NSNumberFormatter alloc] init];
[formatter setNumberStyle:NSNumberFormatterDecimalStyle];
NSString *formattedString = [formatter stringFromNumber:[NSNumber numberWithFloat:[textt floatValue]]];
textField.text = formattedString;
return NO;
}

Answer 1

it does the job for you, shame on me I could have done it better, but I hope someone can give you a more elegant solution for this issue. (e.g. using regexp or something)
- (BOOL)textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string{
NSNumberFormatter *_formatter = [[NSNumberFormatter alloc] init];
[_formatter setNumberStyle:NSNumberFormatterDecimalStyle];
NSMutableString *_pureNumber = [NSMutableString stringWithString:[textField.text stringByReplacingCharactersInRange:range withString:string]];
[_pureNumber replaceOccurrencesOfString:_formatter.groupingSeparator withString:#"" options:NSCaseInsensitiveSearch range:NSMakeRange(0, _pureNumber.length)];
[textField setText:[_formatter stringFromNumber:#([_pureNumber doubleValue])]];
return NO;
}
so, the general idea is you need to convert back your textt to a number.
the auto-parser cannot do it for you, becasue the after 1,234 the 1,2345 is not a valid number in this formatter, that is why you have got the very first number only, simply the parser chucks everything after the comma , away. (that is a groupingSeparator in this formatter).