iPhone Core Data - Import additional content

I'm in the position of looking at over the air distribution of additional content for our Core Data centric app. We need to find a good way to encapsulate new additional content bundles for import into the app.

I'm considering the following:

Option 1> Creating .sql files with insert statements to update the underlying SQ开发者_StackOverflowLite layer directly (we get these as a by product of creating our content anyway).

Option 2> Distribution the new content in full .sqlite files, with which to create temporary managed object contexts and copy the data into the main context via the core layer. On the outset this seems like an expensive option compared the "as lean as it can be" option 1.

Can anyone suggest any other options or recommend the best approach from experience with this?

You could ship the modules as pre-processed SQLite persistent stores. These modules could then be attached to your app's store coordinator at startup. Kind of like loading plugins.

If the content really must live in the main store, you could import the content from one store to the other in the background, or something.

Maybe that's what you're suggesting by your option #2...

Another valid approach is to define a more generic external data format, eg something in JSON, XML, CSV, even vanilla SQLite, ship your data modules in the format, and import from there into your app's persistent store.

Your option #1 is risky, as it depends knowing the internal schema of the CD SQLite store, which Apple reserves the right to change at their discretion without telling you. I wouldn't ship on this option.

I'd go with either importing JSON or shipping pre-baked SQLite persistent stores.

Option1 is very dangerous because the Core Data SQLite schema is undocumented and subject to change without warning (assuming you can accurately reverse engineer it in the first place.)

Option 2 is your best option. It might seem expensive but remember that Core Data is first and foremost an object graph management API and only secondly a persistence API. Object graphs have not only data but also relationships and behaviors. The only reliable way to add objects to an object graph is to do so while the graph is "alive" i.e. by instantiating live objects and inserting them into the live (active) graph.

Writer/programmer Marcus Zarra has written about this issue several times and explains how to use configurations and even "plugin" data models and stores to import and export graphs from Core Data.