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

Use NSNumberFormatter.

Specifically:

NSNumberFormatter *formatter = [NSNumberFormatter new];
[formatter setNumberStyle:NSNumberFormatterDecimalStyle]; // this line is important!

NSString *formatted = [formatter stringFromNumber:[NSNumber numberWithInteger:2000000]];

[formatter release];

By default NSNumberFormatter uses the current locale so the grouping separators are set to their correct values by default. The key thing is to remember to set a number style.

Answer 2

Even easier:

NSNumber *someNumber = @(1234567890);
NSString *modelNumberString = [NSString localizedStringWithFormat:@"%@", someNumber];
NSLog(@"Number with commas: %@", modelNumberString);

coworker just taught me this today. #amazing

Answer 3

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;\
})()\
)

Answer 4

There's a static method on NSNumberFormatter that does just what you need:

int aNum = 2000000;
NSString *display = [NSNumberFormatter localizedStringFromNumber:@(aNum)
                                                     numberStyle:NSNumberFormatterDecimalStyle];

This way is a little more succinct than creating a new NSNumberFormatter if you don't need to do any additional configuration of the formatter.

Answer 5

Swift version

let formatter = NSNumberFormatter()
formatter.numberStyle = .DecimalStyle
formatter.maximumFractionDigits = decimalPlaces
let result = formatter.stringFromNumber(NSNumber(double: 8.0))

By http://ios.eezytutorials.com

Answer 6

Don't do your own number formatting. You will almost certainly not get all the edge cases right or correctly handle all possible locales. Use the NSNumberFormatter for formatting numeric data to a localized string representation.

You would use the NSNumberFormatter instance method -setGroupingSeparator: to set the grouping separator to @"," (or better yet [[NSLocale currentLocale] objectForKey:NSLocaleGroupingSeparator]; thanks @ntesler) and -setGroupingSize: to put a grouping separator every 3 digits.