title: Getting "Undefined symbols" when trying to use EventKit?
body: <p>I am trying to use EventKit based around the doco &amp; SimpleEKDemo application, however I am getting the following single error. </p>
  
  <p>What does this error mean and what steps would be recommended for troubleshooting (first time I've had such a linking error &amp; I'm a bit lost - I've parsed through my code versus teh example code and I can't see any obvious differences).</p>
  
  <pre><code>Undefined symbols:
    "_OBJC_CLASS_$_EKEventStore", referenced from:
        objc-class-ref-to-EKEventStore in AppointmentListController.o
  ld: symbol(s) not found
  collect2: ld returned 1 exit status
  </code></pre>
  
  <p>Note that in the header file from the controller I'm using the event kit code I do have:</p>
  
  <pre><code>#import &lt;EventKit/EventKit.h&gt;
  #import &lt;EventKitUI/EventKitUI.h&gt;
  </code></pre>