title: Type "SwiftClass" cannot conform to protocol "ObjcProtocol" because it has requirements that cannot be satisfied
body: <p>I have an Objective-C protocol which I'm trying to implement in a Swift class. For example:</p>
  
  <pre><code>@class AnObjcClass;
  
  @protocol ObjcProtocol &lt;NSObject&gt;
      - (void)somethingWithAnArgument:(AnObjcClass *)arg;
  @end
  </code></pre>
  
  <p>When I try to conform to it in a Swift class like this:</p>
  
  <pre><code>@objc class SwiftClass: NSObject, ObjcProtocol {
      // ...
  }
  </code></pre>
  
  <p>I get the following scary compiler error:</p>
  
  <blockquote>
    <p>Type "SwiftClass" cannot conform to protocol "ObjcProtocol" because it has requirements that cannot be satisfied.</p>
  </blockquote>
  
  <p>How do I resolve this?</p>