Maarten Billemont is attempting to build out a well documented system to work
around iCloud’s Core Data syncing issues1. It’s an impressive SDK
with a clear API for what could go wrong and what you’d need to handle.
His library will watch for iCloud store corruption and tear down and rebuild
the store automatically, notifying all other devices to use the new store in
the process. It’s a great example of wrapping “scar tissue” around an
unreliable external dependency. He’s encoded all the things that could go wrong
as well named messages that are sent to you as the delegate, and spells out the
default recovery behavior or how you can inject your own.