Error StoreKit.h with Xcoce

When using Xcode, I have the command #include “StoreKit/StoreKit.h”. And when I run the simulator, it error: Unknown type name ‘NSString’ in some files of Foundation.framework.
According to some help, I changed the *.cpp file to *.m. But when I run it again, I get an error " ‘stack’ file not found" ở file CCDirector.h

How to way with this problem?
Thank you very much!