Mac Forum / Programming / Mac Programming / April 2008

There is a new feature in OS X 10,5 (Leopard) that affects your
application:

Preferences Sync.

Preferences Sync is a new feature of Sync Services manager and .Mac,
that lets the user sync the contents the directory of
${HOME}/Library/Preferences between multiple Macs.

You probably have a checklist of tasks you must attend to, to get your
application program ready to ship.

Please add this item:

Look at the preferences you write to NSUserDefaults. Consider what
happens when a user uses .Mac to sync preferences to another machine.
Should any preferences not be synced?

For example, if your program checks for updates, you don't want the time
of last check to be synced, because an old version might never check.

Here's how to control which preferences will be exempt from Preferences
Sync:

In your app's Info.plist add:

...
<key>com.apple.PreferenceSync.ExcludeSyncKeys</key>
<array>
<string>SULastCheckTime</string>
... other keys here ...
</array>

...

See:

http://developer.apple.com/documentation/Cocoa/Conceptual/SyncServices/Ar
ticles/SyncingPreferences.html

for more information.