Get last 2 characters of a string?

Say I have a string:

NSString *state = @"California, CA";

Can 开发者_Python百科someone please tell me how to extract the last two characters from this string (@"CA" in this example).

NSString *code = [state substringFromIndex: [state length] - 2];

should do it

Swift 4:

let code = (state as? NSString)?.substring(from: state.characters.count - 2)