title: NSInvocationOperation with return value (BOOL)
body: <p>hi i have these invocation operation:</p>
  
  <pre><code>NSInvocationOperation *operation = [[NSInvocationOperation alloc] 
               initWithTarget:ndParser selector:@selector (parseUrl:)
               object:[NSString stringWithFormat:@"http://URL%@",var]];
  </code></pre>
  
  <p>my method:</p>
  
  <pre><code>- (BOOL) parseUrl:(NSString *)URL;
  </code></pre>
  
  <p>should throw back bool....</p>
  
  <p>how can i catch this value?</p>
  
  <p>regards</p>