title: Error arm64 Xcode and Parse
body: <p>Hi friend have this error: </p>
  
  <pre><code> "_OBJC_CLASS_$_PFInstallation", referenced from:
        objc-class-ref in ParseExampleAppDelegate.o
  
   "_OBJC_CLASS_$_PFPush", referenced from:
        objc-class-ref in ParseExampleAppDelegate.o
  
   "_OBJC_CLASS_$_PFQuery", referenced from:
        objc-class-ref in ViewController.o
        objc-class-ref in ParseExampleViewController.o
        objc-class-ref in Buongiorno.o
        objc-class-ref in ParseImageViewController.o
        objc-class-ref in Compleanno.o
        objc-class-ref in Buonanotte.o
  
   "_OBJC_CLASS_$_PFUser", referenced from:
        objc-class-ref in LoginViewController.o
  
   "_OBJC_CLASS_$_Parse", referenced from:
        objc-class-ref in ParseExampleAppDelegate.o
  
       (maybe you meant: _OBJC_CLASS_$_ParseExampleViewController, _OBJC_CLASS_$_ParseExampleCell , _OBJC_CLASS_$_ParseImageViewController , _OBJC_CLASS_$_ParseExampleAppDelegate )
  
  ld: symbol(s) not found for architecture x86_64
  
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  </code></pre>