In the challenge section it uses the following:
NSRange r = [n rangeOfString:@“AA” options:NSCaseInsensitiveSearch;
then, below that another line of code uses the “r” in the following way:
if (r.location != NSNotFound) [
I’m trying to understand how this works and can’t find in the book where this is described. If you could direct me where to look I would appreciate this.