Synchronize Core Data with paginated Web Service

Question

So here's my problem. I have a pinterest-like application with a collection view that shows images.The "pins" al downloaded from a web service and stored in core data. This web service returns the data organized in pages.

What's the correct way to face this problem? If data were all stored in core data, I could implement as NSFetchedResultsController to fetch a batch of 10 or 20 pins, but each batch needs to make the appropriate request to the web service. I've also been looking into NSIncrementalStore, which also seems promising, but I still don't know how would that work.

Right now, I have the web service working, the core data model implemented and a special class called DataManager that is responsible of the managedObjectContext, inserting, fetching, deleting, etc., from the database. I'm implementing the FetchedResultsController creator inside this class, but I still don't understand how to implement the incrementalStore or the web service call.

Any idea on how to implement this architecture will be highly appreciated.

Best regards

Answer 1

Do not use NSIncrementalStore, that is not what you are looking for. NSIncrementalStore is an abstraction that allows you to implement your own store type within Core Data.

What you are looking for is how to cross the gap between how web apps "think" and how a mobile app should "think".

Personally, I would build NSOperation instances that fetch those pages and stick them all (or a reasonable number of them) into Core Data and let your mobile application act like it should, showing all the data available.

Pagination is a lazy web solution for being unable to cache data locally within the web browser. Your application is not a web browser, don't follow those terrible UI conventions.