iOS return one digit fragment from NSString

Question

I can't find an easy way to generate a one digit sized substring from an NSString. The NSString looks like "(N3)" but I need to store just the number portion "3" in an substring. Using:

NSString *subString = [dis substringFromIndex:2];

returns "3)".

Any ideas?

Answer 1

Well, if the string is one digit and its position is invariant, you could just use:

int Foo(NSString * dis) {
 const unichar c = [dis characterAtIndex:2];
 assert(isdigit(c) && "not a number");
 return c - '0';
}