title: How to get the PID from a ProcessSerialNum in OSX 10.9?
body: <p><code>GetProcessPID</code> was marked deprecated in OSX 10.9 along with the note:</p>
  
  <blockquote>
    <p>Use the processIdentifier property of the appropriate
    NSRunningApplication object.</p>
  </blockquote>
  
  <p>The problem is the constructing class methods for <code>NSRunningApplication</code> do not have a way to get a <code>NSRunningApplication</code> by a <code>ProcessSerialNum</code>, only by PID or bundle name.</p>
  
  <p>Bundle name is too ambiguous (there could be multiple instances) and I don't have the PID (it's what I want).</p>
  
  <p>In OSX 10.9, is there a way to get the PID when you have a PSN?</p>