I am quite new here but have been digesting the forum and getting answers to things I hadn't even considered yet!
In any case, being a newb, I know there are lots of unanswered questions about game design on the forum
having trolled through about 300 pages now.
I came across this cool document I believe should be required reading for anyone beginning at attempting a game of some sort:
This page should cover a lot of basic questions for others who are looking for this kind answer.
Although the code examples are in C++ all the methods can be applied in objective-c with very little effort.
Anyway, I am really grateful that there are people out there sharing these sort of recipes, otherwise it would
be incredibly hard slog!