I learned that NSUbiquitousKeyValueStore is always available, also when no iCloud account is set up. This makes me believe I can safely store essential data in it, without keeping a copy in NSUserDefaults.
However, in their documentation, Apple says the following:
Avoid using this class for data that is essential to your app’s behavior when offline; instead, store such data directly into the local user defaults database.
Do I overlook issues that might arise when not using NSUserDefaults (or another offline store) as back-up? Or is Apple being overprotective and is it safe to rely on NSUbiquitousKeyValueStore?
Julien commented the following about this question:
What this means is that you should not rely on this store to be your local truth but more of a simple sync communication channel between your devices.