Retain the returnValues so they aren't released between the time they are returned
and the time they are either retained by the caller, or in the case of non ARC calling
code possibly not retained at all because the receiver was expecting a retained value.
Retain the returnValues so they aren't released between the time they are returned and the time they are either retained by the caller, or in the case of non ARC calling code possibly not retained at all because the receiver was expecting a retained value.