title: Method not found (return type defaults to 'id')
body: <p>Does anyone know what this LLVM warning means:</p>
  
  <pre><code>Method '-retry' not found (return type defaults to 'id') in sourceFile.m
  </code></pre>
  
  <p>I get this warning on the following line of sourceFile.m:</p>
  
  <pre><code>[self.operation retry];
  </code></pre>
  
  <p>My class has a variable 'operation', which is a custom class extending NSOperation.</p>
  
  <pre><code>MyCustomOperation* operation;
  
  @property (nonatomic, retain) MyCustomOperation* operation;
  </code></pre>
  
  <p>My custom operation class has a method:</p>
  
  <pre><code>- (void) retry;
  </code></pre>
  
  <p>Everything seems to work, but I'd sure love to get rid of my warnings.</p>
  
  <p>Thanks!</p>