UserDefaults in system preference pane installed for multiple users in OSX...

Question

Hi I have a background-only app that is controlled via a preference pane in the system preferences. To communicate between pref pane and app I use distributed notifications. User defaults are shared via [NSUserDefaults addSuiteNamed:]. This all works out very well.

The problem occurs when the user installs the pref pane "for all users", when prompted by the system preference pane. In this case prefs get written to ~/Library/Preferences/, same as when installed "for this user only". (I think this is the correct behavior.) However, when the prefpane reads a default key, the prefpane seems to be looking at /Library/Preferences/, not in the user's home directory.

To sum it up:

• prefs pane installed in: ~/Library/PreferencePanes/
  
  • Defaults written to: ~/Library/Preferences/
  • Defaults read from: ~/Library/Preferences/
• prefs pane installed in: /Library/PreferencePanes/
  • Defaults written to: ~/Library/Preferences/
  • Defaults read from: /Library/Preferences/

Could anyone shed some light as to where things go wrong?

Thanks, Kolja

Answer 1

Preference panes which get installed "for all users":

1. Require administrator authentication (the user installing the pref pane should be prompted for an admin password)
2. Get installed in /Library/PreferencePanes

Do both of these things occur for your pref pane? It looks like preferences should indeed be placed in ~/Library/Preferences, by example of looking at my current configuration. Therefore the correct solution (I think) is for the preference pane to be looking in your home folder's Preferences folder, not the hard disk root directory. I'm not sure how to tell the pref pane to look there, though.

Answer 2

You have essentially the same design as Growl. We use CFPreferences to read and write the user's preferences. See GrowlPreferencesController and the macros in GrowlDefinesInternal.h. The distributed notification cues both the background app and the prefpane to re-read the preferences.

(Don't take it quite as far as we do, though—it's fine to use NSNumber, NSDictionary, etc. with Core Foundation, and it's much easier to read.)