I'm getting several linker errors in the implementation of my AppController class. It's not finding any of the Core Animation classes or constants with several Apple Mach-O Linker errors such as: "_kCAEmitterLayerAdditive", referenced from:" I've cleaned and rebuilt to no effect. I also have kept all of my Developer files in their default locations to my knowledge. Also, when I run Apple's sample code using Core Animation, it builds fine. In the AppController.h file I'm including at the top: Code: #import <QuartzCore/CoreAnimation.h> just like with the sample code. Any suggestions for how to debug this? Any general suggestions for debugging linking issues (this is an area that I'm not very knowledgeable)? Thanks.