postNotification trigger the function correctly , but userinfo(NSDictionary) has nothing
<p>I used the codes below to notify the menu selection index</p>

<pre><code>    NSDictionary *userInfo=  [NSDictionary dictionaryWithObject:[NSString stringWithFormat:@"123"] 
                                              forKey:@"Index"];
   [[NSNotificationCenter defaultCenter] postNotificationName: @"notifyToMenuSelectionNotification"
                                                    object: userInfo];



-(void)menuSelectionNotification:(NSNotification *)notification
{
  NSLog(@"%@", notification.userInfo);


}
</code></pre>

<p>menuSelectionNotification is triggered correctly,</p>

<p>but NSLog output notification.userInfo is still {null}</p>

<p>Welcome any comment1</p>
