title: Swift 3, NotificationCenter observer missing posted Notification
body: <p>There seems to be a few changes surrounding the NotificationCenter in Swift 3 and I can't seem to quite get it right.</p>
  
  <p>Using:</p>
  
  <pre><code>Apple Swift version 3.0.2 (swiftlang-800.0.63 clang-800.0.42.1)
  </code></pre>
  
  <p>I have a singleton object:</p>
  
  <pre><code>class Notifications {
  
      private static let pipeline = Notifications()
      ...
  </code></pre>
  
  <p>That receives and enqueues items subscribing to <code>NotificationsPipelineProtocol</code>. <em>(They are all pure swift, no Objective-C NSObjects here.)</em></p>
  
  <pre><code>    private func enqueueNotification(_ notification: NotificationsPipelineProtocol) {
          ...
  </code></pre>
  
  <p>in which it adds itself as an observer to the NotificationCenter</p>
  
  <pre><code>        NotificationCenter.default.addObserver(self,
                                         selector: #selector(Notifications.didReceiveNotificationCompletion(_:)),
                                         name: notification.completionNotificationName,
                                         object: notification)
  </code></pre>
  
  <p><strong>NOTE</strong> - <code>notification.completionNotificationName</code> is a computed variable that produces a <code>Notification.Name</code> item.</p>
  
  <p>But when the <code>NotificationsPipelineProtocol</code> item posts to the NotificationCenter:</p>
  
  <pre><code>NotificationCenter.default.post(name: self.completionNotificationName, object: self)
  </code></pre>
  
  <p>The observer does not call it's associated subscribed method:</p>
  
  <pre><code>    @objc private func didReceiveNotificationCompletion(_ notification : Notification) {
      ...
  </code></pre>
  
  <p>Might you know why? Is there a way to check to see in NotificationCenter to which notifications a particular item is subscribed to? Is perhaps the singleton object dropping it's observation? Maybe the #selector has been improperly formatted?</p>
  
  <p>XCode gives me no warnings or errors.</p>
  
  <p>Thanks in advance.</p>