Hey!

I Don't have lots of Cocoa development experience so i'll try and say it lightly:
I've failed to find any proof of objects being removed from registeredObjects. This leads me to the unexperienced conclusion that any object, once rendered while auto update is enabled, will never be released.

NUI is awesome, and i'd love to fix this issue and submit a pull request, I just wanted to affirm that it is indeed a problem that needs to be solved.

Thanks!