title: Is it a possible for an objective-c class to implement a swift protocol in the .h
body: <p>Is it a possible for an <code>Objective-C</code> class to implement a <code>Swift</code> protocol in the <code>.h</code> so that other <code>Swift</code> classes can reference the <code>Objective-C</code> class by the <code>Swift</code> protocol type?</p>
  
  <p>Let <code>MySwiftProtocol</code> be the <code>Swift</code> protocol type, now assume I have this in <code>.h</code> for my class:</p>
  
  <pre><code>@protocol MySwiftProtocol;
  @interface MyObj : NSObject&lt; MySwiftProtocol&gt;
  </code></pre>
  
  <p>Then I'll get a warning: <code>cannot find protocol definition for MySwiftProtocol</code><br>
  The warning is no good, so that doesn't work.</p>
  
  <p>So let's assume I do this in the <code>.m</code> and remove the references to the protocol in the <code>.h</code>.</p>
  
  <pre><code>@interface MyObj () &lt;MySwiftProtocol&gt;
  </code></pre>
  
  <p>Then I end up not being able to cast objects of type <code>MyObj</code> to type <code>MySwiftProtocol</code> in <code>Swift</code> classes.  </p>
  
  <p>So neither approach above works. </p>
  
  <p>Please help!</p>