Replace last comma in string with an "and". (Objective-C)

Question

I'm looking for a good way in Objective-C to replace the last comma in a string with the word "and". Any suggestions?

"Red, Green, Blue, Yellow"

becomes

"Red, Green, Blue and Yellow"

Answer 1

NSString *str = @"....";  
NSRange lastComma = [str rangeOfString:@"," options:NSBackwardsSearch];

if(lastComma.location != NSNotFound) {
    str = [str stringByReplacingCharactersInRange:lastComma
                                       withString: @" and"];
}