I am building a unit test. The target of this unit test is my framework. My framework linked with couple of static libraries. When the test is running in simulator with host app it works fine. But when I try to test without host app I get following error from linker. PS: My test's xcconfig is similar to the host app's, and I can build the host app successfully. Undefined symbols for architecture arm64: "__mh_execute_header", referenced from: So what is __mh_execute_header and what framework/library it is defined in? Thanks for any help!