title: xcode 10.1 Undefined symbols for architecture arm64
body: <p>I already gone so many SO threads with similar issue but none of them seems to resolve my error.</p>
  
  <p>In our project we have multiple "TARGETS". Only one of the target - the very first target created ever - is archiving properly. When I try to archive other target we encounter this error</p>
  
  <pre><code>Undefined symbols for architecture arm64:
    "_OBJC_CLASS_$_DynamicEventData", referenced from:
        objc-class-ref in DataManager.o
        objc-class-ref in DataReader.o
    "_OBJC_CLASS_$_DynamicDataService", referenced from:
        objc-class-ref in DataManager.o
    "_OBJC_CLASS_$_DynamicDataConfig", referenced from:
        objc-class-ref in DataManager.o
  ld: symbol(s) not found for architecture arm64
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  </code></pre>
  
  <p>I did compare the <code>Build Setting</code> of the <em>working target</em> to the other targets but all of them are equal. I checked the header files and they exists in our project directory. I tried to manually add the header files' path to <code>Header Search Paths</code> but same result still getting the error.</p>
  
  <p>Any idea? I really need to resolve this to export an ipa file.</p>
  
  <p>Thanks!</p>