title: iPhone - respondToSelector returns NO but method is implemented
body: <p>I have a class that declares and implements this :</p>
  
  <pre><code>- (void) callbackme:(OneClass*)p1 error:(NSString*)errStr {
  
  }
  </code></pre>
  
  <p>and that calls in an instance method :</p>
  
  <pre><code>[self.obj oneAction:@"a string" sendAnswerToObject:self]; // obj is a custom class
  </code></pre>
  
  <p>in oneAction method of the custom class, I have :</p>
  
  <pre><code>- (void) oneAction:(NSString*)p1 sendAnswerToObject:(id)listener {
  
       if (listener != nil &amp;&amp; ![listener respondsToSelector:@selector(callbackme::)]) 
               NSLog(@"Listener does not respond to selector 'callbackme:error:'");
  }
  </code></pre>
  
  <p>The NSLog is triggered and I don't understand why ?</p>
  
  <p>The listener must be an id as it can be any object instance of any class.</p>