title: What does a "_OBJC_CLASS_$_CATransaction, referenced from:" compile-time error mean?
body: <p>Can anyone please tell me what is this error, I am trying to compile on xcode</p>
  
  <blockquote>
    <p>"_OBJC_CLASS_$_CATransaction",
    referenced from:</p>
  
  <pre><code>  objc-class-ref-to-CATransaction in RefreshTableViewHeader.o
  </code></pre>
  </blockquote>
  
  <p>And this error</p>
  
  <blockquote>
    <p>"_kCATransactionDisableActions",
    referenced from:</p>
  
  <pre><code>  _kCATransactionDisableActions$non_lazy_ptr
  </code></pre>
    
    <p>in RefreshTableViewHeader.o</p>
  
  <pre><code> (maybe you meant: _kCATransactionDisableActions$non_lazy_ptr)
  </code></pre>
    
    <p>ld: symbol(s) not found</p>
    
    <p>collect2: ld returned 1 exit status</p>
  </blockquote>
  
  <p>Google was of no help.</p>
  
  <p>Am I missing any framework...?</p>