title: How to declare unknown enum in header?
body: <p>I know you can use the <code>@class</code> word to declare an unknown class in an objective-c header file. Is there a way to declare an unknown <code>enum</code> inside a header class?</p>
  
  <p>For instance, is there a way to prevent the compile error for <code>someEnum</code>?</p>
  
  <pre><code>#import &lt;Foundation/Foundation.h&gt;
  
  @class UnknownClass;
  
  @interface Foo
  
  @property (nonatomic, strong) UnknownClass *someObject;
  @property (nonatomic) UnknownEnum someEnum;
  
  @end
  </code></pre>