Finding out whether a string is numeric or not

Question

How can we check if a string is made up of numbers only. I am taking out a substring from a string and want to check if it is a numeric substring or not.

NSS         


        

Answer 1

to be clear, this functions for integers in strings.

heres a little helper category based off of John's answer above:

in .h file

@interface NSString (NumberChecking)

+(bool)isNumber:(NSString *)string;

@end

in .m file

#import "NSString+NumberChecking.h"

@implementation NSString (NumberChecking)

+(bool)isNumber {
    if([self rangeOfCharacterFromSet:[[NSCharacterSet decimalDigitCharacterSet] invertedSet]].location == NSNotFound) {
        return YES;
    }else {
        return NO;
    }
}

@end

usage:

#import "NSString+NumberChecking.h"

if([someString isNumber]) {
    NSLog(@"is a number");
}else {
    NSLog(@"not a number");
}