NSNumberFormatter only allowing 4 digits - objective-c

Question

Please can you tell me why my NSNumberFormatter is only letting me use 4 digits (i.e £2,222) instead of infinite digits?
- (BOOL) textField:(UITextField *)textField shouldChangeCharactersInRange:(NSRange)range replacementString:(NSString *)string {
NSString *input = [textField.text stringByAppendingString:string];
[textField setText:[self numberFormattedString:input]];
return NO;
}
- (NSString *) numberFormattedString:(NSString *)str {
str = [str stringByReplacingOccurrencesOfString:#"£" withString:#""];
NSNumberFormatter *formatter = [[[NSNumberFormatter alloc] init] autorelease];
[formatter setNumberStyle:NSNumberFormatterCurrencyStyle];
NSLocale *locale = [[NSLocale alloc] initWithLocaleIdentifier:#"en-UK"];
[formatter setLocale:locale];
[locale release];
[formatter setMaximumFractionDigits:3];
[formatter setMinimumFractionDigits:0];
return [formatter stringFromNumber:[NSNumber numberWithFloat:[str floatValue]]];
}
Edit--
When I type a fifth digit, having already 4 digits inside the UITextField, the textField's text is reset back to fifth digit typed alone.
E.G
I enter 1000 into the UITextField, I then enter a further digit of 5. As 5 is the fifth digit, the UITextField's text gets reset to the fifth digit alone. The UITextField now displays '5'.
TIA.
XcodeDev

Answer 1

The problem is that a comma is breaking [NSString floatValue]. When you get to entering the fifth digit, str ends up looking something like 1,0005, which floatValue converts to a value of 1 since it doesn't know how to deal with the comma and/or the fact that there are too many digits after it. Add this code
str = [str stringByReplacingOccurrencesOfString:#"," withString:#""];
as the first or second line of numberFormattedString and it will work.

Answer 2

What's probably happening is that as the user types, the formatter is inserting commas at the thousand marks. You aren't stripping those out when you do the reformatting like you are with the pound sign, so at some point the formatting function is being given a string like "1,000".
When you try to get the floatValue of that to convert it back into an NSNumber for reformatting, floatValue returns 1 because it can't parse commas.
Solution: add this extra line to your formatting function:
str = [str stringByReplacingOccurrencesOfString:#"," withString:#""];