This occured to me when reusing the Recipe code from the previous chapter. During building, I got this error:
Undefined symbols for architecture i386: “OBJC_CLASS$_PRPRecipeSource”, referenced from: objc-class-ref in PRPAppDelegate.o ld: symbol(s) not found for architecture i386 clang: error: linker command failed with exit code 1 (use -v to see invocation)
After googling around, discovered that during the add, I must of missed the “Add to targets” check box - the added source code was not added to the Compile Sources section in the Project’s Build Phase tab:
After I’ve included the additional source files (the .m), this solved the linker issue.