Receive CFMessagePortSendRequest notifications

[Benjamin Stiglitz]

> I'm now trying to subscribe to the notifications, in case the values
> change not due to my program and a notification is sent.
> Eg, if the user change the setting via System Preferences.app, I want
> to catch the notification sent by System Preferences.app.

Unfortunately for you, these aren’t notifications at all; they’re messages sent directly to the port registered with that name.  There’s no way to snoop the messages short of code injection.

Since anything that changes the settings will update the plist, you might want to watch that instead.

Good luck,
-Ben