title: Xcode: Undefined symbols for architecture arm64 error
body: <p>In my Xcode 5 project I use RestKit for REST communication.
  Everything works fine with the simulators, but generating the ipa file, I get the following error:</p>
  <pre><code>ld: warning: ignoring file /Users/joseph/Library/Developer/Xcode/DerivedData/XXXXXXXXXX-gdwdekevxtdfivfpsnmyykeqhulk/Build/Products/Debug-iphoneos/libRestKit.a, missing required architecture arm64 in file /Users/joseph/Library/Developer/Xcode/DerivedData/XXXXXXXXXXXXX-gdwdekevxtdfivfpsnmyykeqhulk/Build/Products/Debug-iphoneos/libRestKit.a (2 slices)
  Undefined symbols for architecture arm64:
    &quot;_OBJC_CLASS_$_RKRelationshipMapping&quot;, referenced from:
        objc-class-ref in classname-xxx.o
    &quot;_OBJC_CLASS_$_RKObjectMapping&quot;, referenced from:
        objc-class-ref in classname-xxx.o
    &quot;_OBJC_CLASS_$_RKRequestDescriptor&quot;, referenced from:
        objc-class-ref in classname-xxx.o
    &quot;_OBJC_CLASS_$_RKObjectManager&quot;, referenced from:
        objc-class-ref in classname-xxx.o
    &quot;_OBJC_CLASS_$_RKResponseDescriptor&quot;, referenced from:
        objc-class-ref in classname-xxx.o
  
    &quot;_RKStatusCodeIndexSetForClass&quot;, referenced from:
        -[classname-xxx classname-Method] in classname-xxx.o
        -[classname-xxx classname-Method] in classname-xxx.o
        -[classname-xxx classname-Method] in classname-xxx.o
        -[classname-xxx classname-Method] in classname-xxx.o
        -[classname-xxx classname-Method] in classname-xxx.o
    &quot;_RKMIMETypeJSON&quot;, referenced from:
        -[classname-xxxinitWithURLBase:timeOut:] in classname-xxx.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>If in RestKit project, I change in &quot;Build Settings&quot; -&gt; &quot;Architectures&quot; the &quot;Standard architectures (ARMv7, armv7s)&quot; by Standard architectures (including 64-bit) (ARMv7, armv7s, arm64) option, everything compiles fine . Is this correct?, Does not bring any result, I have to change some other settings.</p>