How to check if NSString is contains a numeric value?

Question

I have a string that is being generate from a formula, however I only want to use the string as long as all of its characters are numeric, if not that I want to do something dif

Answer 1

Something like this would work:

@interface NSString (usefull_stuff)
- (BOOL) isAllDigits;
@end

@implementation NSString (usefull_stuff)

- (BOOL) isAllDigits
{
    NSCharacterSet* nonNumbers = [[NSCharacterSet decimalDigitCharacterSet] invertedSet];
    NSRange r = [self rangeOfCharacterFromSet: nonNumbers];
    return r.location == NSNotFound && self.length > 0;
}

@end

then just use it like this:

NSString* hasOtherStuff = @"234 other stuff";
NSString* digitsOnly = @"123345999996665003030303030";

BOOL b1 = [hasOtherStuff isAllDigits];
BOOL b2 = [digitsOnly isAllDigits];

You don't have to wrap the functionality in a private category extension like this, but it sure makes it easy to reuse..

I like this solution better than the others since it wont ever overflow some int/float that is being scanned via NSScanner - the number of digits can be pretty much any length.