Check if NSString contains alphanumeric + underscore characters only

Question

I\'ve got a string that needs to be only a-z, 0-9 and _

How do I check if the input is valid? I\'ve tried this but it accepts letter like å,ä,ö,ø etc.

NS         


        

Answer 1

this is a quick helper if it helps

-(BOOL)isString:(NSString *)s{
    char letter = 'A';
    //BOOL isLetter=NO;
    for (int i=0; i<26; i++) {
        NSString *temp = [NSString stringWithFormat:@"%c",letter+i];
        if ([s isEqualToString:temp]) {
            return YES;
        }
    }
    return NO;
}