The bottom line is, this change is mainly to save Apple the bandwidth and storage costs associated with iCloud backups. It's a straightforward solution to offer developers a programmatic way to opt-out. With maps or news readers, I might want to keep a local copy indefinitely on my iPhone but do I want these constantly backed up? No. I wouldn't mind re-downloading them when I upgrade my phone. But do I want them deleted arbitrarily when storage runs low? No because I have no control over it. Just imagine your browser cache being cleared by the OS at random moments when other applications trigger an arbitrary file limit and causing errors at random moments.<p>If Apple could offer a way for users to allocate a fixed amount of space for certain apps and opt out of syncing certain data per app, it wouldn't be a problem.<p>What's more this change suddenly happened. There was no bright red warning sign going into the release, these developers are finding out the hard way.
I read all the comments in this thread, and it surprises me that so many people have a hard time imagining a case where the user wants to store several gigabytes of data locally - maybe 10 gigs - but not have that data backed up to a cloud.
As a user, I can't imagine a class of data that is so important it should never be reclaimed to save space, and is so worthless it should not be backed up.<p>The important use case is what should happen when you lose your phone/tablet and buy a replacement. Or wipe it. Should the data be restored or should it be lazily regenerated/redownloaded?<p>For map cache data, re-download it. Otherwise, the map app runs fast at the expense of all the other apps on the device.<p>Data that has been preloaded to read offline (e.g., Instapaper) should be stored in Documents. If I lost my iPad, I would not want to have to manually reload a bunch of articles when I got a replacement.<p>I understand that IOS5 has gratuitously broken a lot of apps, and the new regime may have been communicated badly. (May have. I'm not an IOS developer; I don't know what the developer documentation says.) But IOS is user-centric, not dev-centric.
Apple wants Cache (stuff that can be re downloaded and not core to the experience, just to improve performance) to actually be deletable when space is low. A valid point.<p>Developers want a place to store app information that is critical and sometimes a very important part of the app(example main feature of instapaper is to view offline content). This should not be backed up since its redundant and when the phone needs to be restored(rarely) this data can be re-downloaded. Also backing up will be slow and destroy user experience.<p>Solution make another location which is used for storing the data(not backed up) so then all are happy. Maybe you can have data from hidden directories not backed up inside the Documents directory. Then Apple can delete caches in apps like browsers. User critical data like settings can be backed up and app critical data that need not be backed up can also exist
Maybe i'm not understanding this correctly (I'm not an iPhone dev), but why don't you just store the data in the Documents folder ? Or maybe make it the user's choice:
1. Save data in the Documents folder - > slower itunes backup
or
2. Save data in the Caches folder -> Arbitrarily deletion of data
Not to trivialize the problem, but I can't be the only one to think "Hey, maybe it's not a good idea to store permanent data in a directory called Caches".