I can tell you for certain that the OS swipe animations are not pre-rendered (you can easily tell, sometimes one or both of the views involved are animated for

I can tell you for certain that the OS swipe animations are not pre-rendered (you can easily tell, sometimes one or both of the views involved are animated for example), and I highly doubt anyone would do that. What would be the purpose? It's much more complex to handle, and there's no benefit.