I am using the source code from https://github.com/jab5990/TestCDiCloud.git. Apparently this source code is the sample code from the WWDC 2012 Session #227 called Using iCloud with Core Data. The original source code does not seem to be available on Apple's website any longer.
I am new to Core Data and I struggle quite a bit with these concepts. The situation is that the data does not get refreshed while both apps are running:
So on in DetailViewController.m:204 on the iPhone App the Notification NSPersistentStoreDidImportUbiquitousContentChangesNotification
is registered, which should mean that changes from the Mac app should be incorporated.
How do I ensure that the data stays in sync.
In the simulator sometimes you need to use the Debug -> Trigger iCloud Sync menu to trigger the sync. It is not automatic like on iOS devices.
If you keep having issues then try these sample apps which include code for handling iCloud account switches, moving from local to iCloud, making backups, storing and fetching backup files in iCloud, etc...
BTW that wwdc2012 session is old so I would look at the more recent wwdc2013 session 207 video for things that have changed in iOS7, OSX 10.9