如何将数据加载到Core Data？

Question

thanks for you help.

I'm attempting to add core data to my project and I'm stuck at where and how to add the actual data into the persistent store (I'm assuming this is the place for the raw data).

I will have 1000 < objects so I don't want to use a plist approach. From my searches, there seems to be xml and csv approaches. Is there a way I can use SQL for input?

The data will not be changed by the user and the data file will be typed in by hand, so I won't need to update these files during runtime, and at this point I am not limited in any type of file - the lightest on syntax is preferred.

Thanks again for any help.

Answer 1

You could load your data from an xml/csv/json file and create the DB on the first lunch of your application (if the DB is not there, then read the data and create it). A better/faster approach might be to ship your sqllite DB within your application. You can parse the file in any format you want on the simulator, create a DB with all your entities, then take it from the ApplicationData and just add it to your app as a resource.

Answer 2

Although I'm sure there are lighter file types that could be used, I would include a JSON file into the app bundle from which you import the initial dataset.

Update : some folks are recommending XML. NSXMLParser is almost as fast as JSONKit (but much faster than most other parsers), but the XML syntax is heavier than JSON. So an XML bundled file that holds the initial dataset would weight more than if it was in JSON.

Answer 3

Considering Apple considers the format of its persistent stores implementation details, shipping a prefabricated SQLite database is not a very good idea. Ie the names of fields and tables may change between iOS versions/phones/whatever hidden variable you can think of. You should, in general, not concern yourself with how this serialization of your data is formatted.

There's a brief article about importing data on Apple's developer site: Efficiently Importing Data

You should ship initial data in whatever format you're comfortable with (XML allows you to do incremental parsing efficiently, which reduces memory footprint) and write an import routine to run if you need to import data.

Edit: With EliBud's comment in mind, I still consider the approach a bit "iffy"... The format of the SQLite database used by Core Data is not something you'd want to generate by yourself (it's weird, simply put, and still not something you should really rely on ).

So you'd want to use a mock app running on the Simulator and use Core Data to create the database (as per EliBud's answer). But you'd still have to import the data into that mock-app! And while it might make sense to do this once on a "real" computer instead of a lot of times on a mobile device (ie copying a file is easy, importing data is hard), you're essentially using the Simulator as an administration tool.

But hey, if it works...