How to include OpenCV in Cocoa Application?

when I create an xCode project with the 'Command Line Tool' c++ stdc++ template, i am able to include and compile opencv headers and run some code.

But i want to use OpenCV in a 'Cocoa Application' context. When created with that template, i got compile errors when I include the OpenCV headers in main.mm. (I already changed main.m to main.mm, the '//NSApplicationMain(argc, (const char **) argv);' is commented out)

One of those errors is: "Statement-expressions are allowed only inside functions"

I suppose its some kind of compiler version error, but when i compare the project build settings i cant find differences.

Do you have any ideas/expertise?