mutualmobile/MMDrawerController — pull request #66 by kcharwood (2013-08-02 14:34:01+00:00)
Title: Unbalanced calls to begin/end appearance transitions using non-animated setCenterViewController:withCloseAnimation:completion: 

If you call this method to set the centre view controller with withCloseAnimation set to NO you will see log messages about "Unbalanced calls to begin/end appearance transitions ... ". It appears in this case MMDrawerController calls the transition methods twice on the current center, i.e.:

beginAppearanceTransition:animated:
beginAppearanceTransition:animated:
endAppearanceTransition
endAppearanceTransition

They are called both in this method directly and also in a nested call to setCenterViewController:animated: because animated is NO. I've worked around this by changing the center controller by setting the property directly (which just calls the private setCenterViewController:animated:).