title: Communicate context in Darwin notifications
body: <p>I have a macOS application which can theoretically run multiple instances. I want to be able to communicate events to the other running instances using the Darwin notification center (via <code>CFNotificationCenter</code>).</p>
  
  <p>I need to not only have a notification name but ideally pass some <code>userInfo</code> at the same time. Unfortunately, as the documentation states:</p>
  
  <pre><code>// - CFNotificationCenterPostNotification(): the 'object', 'userInfo', and 'deliverImmediately' arguments are ignored.
  </code></pre>
  
  <p>Is there any way, or alternative solution which will let me message other running applications and provide a parameter value along with the name of the notification?</p>