Frustrated with iCloud, Apple’s developer community speaks up
I've worked with iCloud in conjunction with Core Data. It's as broken as the article describes, and in fact has gotten worse over time.No one really fully knows WTF is going with iCloud - documentation is basically nonexistent, support unavailable, implementation broken in trivial ways, and error messages inscrutable. I was at an Mac/iOS conference recently where the Core Data iCloud talk morphed from a standard talk into a "here's the mic, anybody have any idea what's going on with this thing" affair. Helpful, but indicative of the state of things.IMO, from having studied this for many, many hours over many moons, is that what Apple is trying to do is fundamentally hard, if not entirely unfeasible. They're trying to replace a smart server with one that's dumb as a doorstop. More specifically, they're trying to emulate a CRUD web service with a file sync engine.Conflict resolution is left up to individual clients, since the server doesn't do any "thinking". Likewise, there is no canonical, authoritative state of the store, since the server doesn't "think", only the clients do. Apple was hoping that by shoving a bunch of diffs of your database onto the server, that clients can reliably reconstruct a sane database by playing them back - except that multiple clients are updating the diffs simultaneously and there is no server-side conflict resolution.Oh, and if stuff fails, there are no regular snapshot states to fall back to, because iCloud is a file store, not a database engine. Your whole store is now corrupt. Enjoy.Oh, and there's no way to nuke the database and start over - there are metadata files that are undocumented or that we don't even have sandbox access to, that interfere with completely destroying the database.At this point you might think "Fine! I'll go to my Settings -> iCloud -> Manage Storage menu and delete everything associated with that app and start it off on a clean slate!"And then you find out that, even today, in iOS 6.1.3 land, there is a bug from iOS 5.0 where if you delete an app's iCloud bucket it can never be created by that app, on that account, ever again. I wish I were exaggerating. In perpetuity. Presumably some state gets fucked and now this app is forever more unable to store anything on iCloud.To make even the most trivial experiment on the iCloud API involves creating a brand new app.iCloud (in so far as it relates to Core Data and document storage) isn't just buggy, isn't just poorly implemented - it's non-functional.