UINavigationController: Rotating the view of a covered controller

Question

I have UINavigationController with two view controllers in it (C1 covered by C2). At some point the device is rotated.

C2 needs to know the size of one of C1's views (C2 is a map for C1's grid and I need to draw the frame in C2's view).

The bounds of C1 are updated when C1 is popped, but I need to get the updated bounds at the time of rotation. Is there a way to cause the C1's view to be updated with the new bounds when it's not the visible controller?

Thanks.