I store the index of the currently selected view in my app's NSUserDefaults. I've noticed after uninstalling then reinstalling from the App Store, the newly installed app seems to remember the view index that was in my NSUserDefaults previously. I haven't configured my app for any iCloud data storage at all, how is this happening?
I'm running iOS 8.
When you look at the source code of MKiCloudSync (which is actually very short), you'll see that it simply stores the entire user defaults dictionary in iCloud whenever any of it changes. It saved to a specific itunes account you used to purchase the app.