Core Data max storage iPhone

1. Is there a limit to how much persistent storage a single iPhone app may consume?

2. What does save set the error argument to if the iPhone hits a per-app limit? What if it hits the hardware limit?

3. Is it possible to limit the number of objects stored for c开发者_开发问答ertain entities? If so, what's a good approach to doing this?

acani, an iPhone app I'm working on, downloads the nearest 20 users from the server and saves them to Core Data. After using the app for a while, the users SQLite table could become rather large. How could I limit it? What should I limit it to? Once this table has reached capacity, how could I make it so that newly downloaded users replace the oldest downloaded users?

Thanks!

Matt

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I don't know the answer to the limits questions, but I would think you would want the maximum amount of data to be limited well ahead of that. There are some iPhone apps (games0 which take up a large amount of storage (I think Myst is something line 1.5G). But if you allowed your database to grow to those sorts of sizes you might start to impact on the storage the user has for their other applications.

I'd be inclined to suggest that your application needs to have some sort of database house keeping implemented. You will have to write this. Either automatically triggered or manually triggered by the user. For example you might want to setup a settings option where the user can specify how many "old" users it wants to preserve. If users are being added automatically based on location, what sort of algorythm would a user most likely want to cull the list with?

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There is a 2GB limit for apps from the App Store but as far as user data goes, you should be able to basically fill the disk. When that happens, your saves will start to fail, I believe with 'NSFileWriteOutOfSpaceError' bubbled up from the PSC.

As far as limiting entity space, there's no Core Data support for this - you'd have to handle it programatically. You could extend the validation system to check for certain conditions (free space, number of entities) and fail an insert or update if these didn't match your criteria.

If you want to delete old users, just sort the results and delete the first/last one.