I have seen similar link error posts to do with transitioning from 3 to 4. I’m doing a new project in 4.2. In my case I was trying to generate an NSManagedObject subclass with an existing subclass “Offering” expecting “Editor/Create NSManagedObject Subclass” to overwrite the existing previously generated subclass. It didn’t overwrite but gave me no errors on the create. Then when did a build it gave me this link error. It seems to have given me duplicate entries in a linker file that i don’t have easy access to.
ld: duplicate symbol _OBJC_METACLASS_$_Offering in /Users/brucesmith/Library/Developer/Xcode/DerivedData/merchantTabbed-dodurzdyrznghdggsqomuyrisqsu/Build/Intermediates/merchantTabbed.build/Debug-iphonesimulator/merchantTabbed.build/Objects-normal/i386/Offering-264ADC039EBDA437.o and /Users/brucesmith/Library/Developer/Xcode/DerivedData/merchantTabbed-dodurzdyrznghdggsqomuyrisqsu/Build/Intermediates/merchantTabbed.build/Debug-iphonesimulator/merchantTabbed.build/Objects-normal/i386/Offering-94BEB7B9756A7A33.o for architecture i386
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Check you haven’t generated the same class to two different locations, for instance one in the root project folder and one in a subfolder.