Xcode：由于体系结构x86_64的未定义符号，构建失败

Question

我当前正在使用Xcode 10.1。 在应用程序中进行构建时，出现以下错误。  谁能告诉我这是什么问题？     我已经添加了所有框架和库。仍然我得到构建错误。

Undefined symbols for architecture x86_64:
  "_OBJC_CLASS_$_Utils", referenced from:
      objc-class-ref in BakerAPI.o
      objc-class-ref in ARZineViewController.o
      objc-class-ref in IssueViewController.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)