Single-Stage vs Two-Stage Animation for iPhone Apps?

Question

What are single-state and two-stage animation for rotating an iPhone window?

This is the \"error\" message I get in the Debugger Console (nothing crashes):

Answer 1

I wasn't over riding any of those two-step functions, but I was calling my own function when I received orientationChanged notifications, and I had this line of code in it. Commenting it out got rid of the warning and allowed the auto rotate to work properly. Auto rotate still worked with this line of code until iOS 4.2, then it broke completely. Spent a lot of time looking for why the built in autoRotate stopped working in 4.2. Maybe this will help someone else.

Commented out this line to make it work:
[[UIApplication sharedApplication] setStatusBarOrientation:currentOrientation animated:YES];