Can parse cache replace core data

Question

I'm building a simple contact directory with CRUD functions, and I want to have editing functionality offline. My database for the contacts will be stored on a Parse.com backend. Would this be possible using the Parse cache functionality, or would it be better for me to resort to using Core Data?

Answer 1

No, it can't. Parse simply caches the results of your queries. This is extremely limiting and not the same as caching all of your PFObjects. For example, say you ran a query for all of your "contacts" PFObjects. The only thing you would be able to do with the cache is run the exact same query again later (and get the exact same result). You couldn't even query for a subset of that cached data.

Another issue is the cached objects will not be updated with any changes your user is making to your PFObjects. For example, say a user is editing contacts offline and your code is calling saveEventually to save those changes to Parse when possible. When you get a cached query result the user's changes will not be reflected in your PFObjects. The same goes for deleted and added PFObjects I believe. This would make offline use terrible. Here is a thread from the Parse forum that touches on this subject:

https://www.parse.com/questions/does-saving-an-object-supposed-to-update-the-local-cache-of-a-query-on-these-objects

I have seen Parse developers mention improved caching of Parse objects coming at some point in the future. However, this feature does not exist yet and there is no knowing when it will come. In the mean time, if you want to support offline use you have to use Core Data or some other local store. FTASync (which I have never used) is designed to sync Parse objects with Core Data:

https://github.com/itsniper/FTASync

You could also write your own code to sync the two sets of data.