title: UIViewController - can't become first responder
body: <p>anyone knows why UIViewController wouldn't become first responder when I run this code:</p>
  
  <pre><code>[self becomeFirstResponder];
  NSLog(@"is first resp: %i",[self isFirstResponder]);
  </code></pre>
  
  <p>In the console, I always see the line: "is first resp: 0"</p>
  
  <p>I HAVE canBecomeFirstResponder method:</p>
  
  <pre><code>- (BOOL)canBecomeFirstResponder {
  return YES;
  }
  </code></pre>
  
  <p>I don't even know where to look next....</p>