title: Is there any harm in creating a "private" instance of NSNotificationCenter?
body: <p>I'm using notifications to provide two-way communication between a pair of objects, where object A makes a request but may get deallocated before object B responds. </p>
  
  <p>NSNotificationCenter is perfect for this, as object A can simply add itself as an observer. When object B responds, it posts a notification, and if object A has disappeared, the notification is merely ignored.</p>
  
  <p>Since the notification is only intended for object A, it would be practical to set up a private instance of <code>NSNotificationCenter</code> for these notifications, instead of posting them on the <code>defaultCenter</code>. The only disadvantage would be additional memory for the NSNotificationCenter instance, but a time savings when notifications are posted on either.</p>
  
  <p>Am I missing anything?</p>