title: XCode 6.1 Missing required architecture X86_64 in file for extern library
body: <p>I have an issue when trying to use an external lib : I can't compile the project as it throws an exception as below.</p>
  
  <blockquote>
    <p>ld: warning: ignoring file /Users/renaudcousin/Documents/XCode/WORK/StimShopPOC/StimShopPOC/libStimshop_SDK.a, missing required architecture x86_64 in file /Users/renaudcousin/Documents/XCode/WORK/StimShopPOC/StimShopPOC/libStimshop_SDK.a (3 slices)
    Undefined symbols for architecture x86_64:
      "_OBJC_CLASS_$_StimshopSDK", referenced from:
          objc-class-ref in ViewController.o
    ld: symbol(s) not found for architecture x86_64
    clang: error: linker command failed with exit code 1 (use -v to see invocation)`</p>
  </blockquote>
  
  <p>I tried lots of solutions found on stackoverflow (but for XCode 5.1 and not as well explained) without any change ... </p>
  
  <p>I also found this topic <a href="https://stackoverflow.com/questions/26552855/xcode-6-1-missing-required-architecture-x86-64-in-file/27175794#27175794">XCode 6.1 Missing required architecture X86_64 in file</a> that exactly correspond to my problem and
  when looking at my lib's architecture with <code>lipo -info</code> command, it seems it's missing <code>i386</code> and <code>x86_64</code>. How could I add them to my library architectures to be able compile ?</p>