title: XCode 7.3.1, "Undefined symbols for architecture arm64"
body: <p>I have a Swift 2.x app that I am trying to use this Obj-C library with:
  <a href="https://github.com/lmirosevic/GBPing" rel="nofollow">https://github.com/lmirosevic/GBPing</a></p>
  
  <p>I have added the header file to my bridging header:</p>
  
  <pre><code>#import "GBPing-master/GBPing/GBPing.h"
  </code></pre>
  
  <p>When I am trying to build, I get this linker error:</p>
  
  <blockquote>
    <p>Undefined symbols for architecture arm64:   "_OBJC_CLASS_$_GBPing",
    referenced from:
          type metadata accessor for __ObjC.GBPing in Pinger.o   "_OBJC_CLASS_$_GBPingSummary", referenced from:
          type metadata accessor for __ObjC.GBPingSummary in Pinger.o ld: symbol(s) not found for architecture arm64 clang: error: linker
    command failed with exit code 1 (use -v to see invocation)</p>
  </blockquote>
  
  <p>I have searched for and found some posts about "symbols not found for architecture arm64" but have not been able to get this working.  I am quite new to iOS development, so XCode &amp; Swift are both fairly new to me (and I have never done Obj-C).</p>
  
  <p>Since I am only using .h and .m files from this library, aren't the needed object files supposed to be built from these?  So why is arm64 not supported and how can I fix it?  </p>
  
  <p><strong>Basically, I just need help getting this GBPing library to compile properly in my Swift app so that I can use it...</strong></p>
  
  <p>Notes: My "Other Linker Flags" setting is empty, but I did try adding $(inherited), which did not help.  I do not want to remove arm64 as an architecture.  Lastly, this is an Enterprise app that will only run on iPad Air 2 and iPad Mini 4 (iOS 9.2 and up)</p>