How to add commas to number every 3 digits in Objective C?

Question

If I have a number int aNum = 2000000 how do I format this so that I can display it as the NSString 2,000,000?

Answer 1

For those who need to do it with strings of numbers and not just integers (I.e. Big Numbers) I made the following macro:

#define addCommas(__string) (\
(^NSString *(void){\
NSString *__numberString = __string;\
NSString *__integerPortion = __numberString;\
NSString *__decimalPortion = @"";\
if ([__string containsString:@"."]) {\
__integerPortion = [__numberString componentsSeparatedByString:@"."][0];\
__decimalPortion = st(@".%@", [__numberString componentsSeparatedByString:@"."][1]);\
}\
int __i = (int)__integerPortion.length-3;\
while (__i > 0) {\
__integerPortion = st(@"%@,%@", substringInRange(__integerPortion, 0, __i), substringInRange(__integerPortion, __i, (int)__integerPortion.length));\
__i -= 3;\
}\
__numberString = st(@"%@%@", __integerPortion, __decimalPortion);\
return __numberString;\
})()\
)