specify the default key-value store object as the object of the notification?

[rsaunders100]

In the docs for NSUbiquitousKeyValueStore it states:

Important When you register for the NSUbiquitousKeyValueStoreDidChangeExternallyNotification notification, always specify the default key-value store object as the object of the notification.

[rastersize]

With that Apple refers to the object returned by +[NSUbiquitousKeyValueStore defaultStore]. This means that you must/should do the following when registering for the NSUbiquitousKeyValueStoreDidChangeExternallyNotification notification:

NSUbiquitousKeyValueStore *store = [NSUbiquitousKeyValueStore defaultStore];
NSNotificationCenter *notifCenter = [NSNotificationCenter defaultCenter];
[notifCenter addObserver:__the_observer__
                selector:@selector(handleNotif:)
                    name:NSUbiquitousKeyValueStoreDidChangeExternallyNotification
                  object:store];

Most likely to ensure that you only receive notifications that you are actually interested in. Unfortunately the "original" MKiCloudSync code (i.e. this repo) does not do this, and a few other things (see issue/pull request #5). Instead I would recommend using pandamonia’s a2’s fork (edit 2013-01-24: same repo the guy just changed his username) instead which not only registers for the notification correctly but also fixes a bunch of other issues (such as which keys to sync).