title: Forward declare a struct in Objective-C
body: <p>I'm creating a protocol, and one of the parameters to a method I'm defining is a <code>CMTime*</code>. I would like to forward declare <code>CMTime</code> as opposed to including it. However, I've tried <code>@class CMTime</code> and it complains that it is redefined elsewhere as a different type of symbol. Documentation says it's a struct. I've tried forward declaring it as </p>
  
  <pre><code>struct CMTime;
  </code></pre>
  
  <p>but it still is complaining that it doesn't know what it is.</p>
  
  <p>Any ideas what I'm doing wrong?</p>