I've got some experience producing Flash games, and for all Flash's faults I find the designer/developer workflow pretty decent.
I can set up a template FLA with placeholder movieclips and code to that independently of a designer/animator doing their thing. When it comes time for integration, I can either compile their animations into my project by using a SWC or by loading SWF's at runtime.
I've had a quick look, but I can't see any tools that offer a similar workflow for iOS game development. Could anyone producing iOS games shed any light on how they're handling designer/animator/developer workflow?