Fetching Initial Data from CloudKit

Question

Here is a common scenario: app is installed the first time and needs some initial data. You could bundle it in the app and have it load from a plist or something, or a CSV file. Or you could go get it from a remote store.

I want to get it from CloudKit. Yes, I know that CloudKit is not to be treated as a remote database but rather a hub. I am fine with that. Frankly I think this use case is one of the only holes in that strategy.

Imagine I have an object graph I need to get that has one class at the base and then 3 or 4 related classes. I want the new user to install the app and then get the latest version of this class. If I use CloudKit, I have to load each entity with a separate fetch and assemble the whole. It's ugly and not generic. Once I do that, I will go into change tracking mode. Listening for updates and syncing my local copy.

In some ways this is similar to the challenge that you have using Services on Android: suppose I have a service for the weather forecast. When I subscribe to it, I will not get the weather until tomorrow when it creates its next new forecast. To handle the deficiency of this, the Android Services SDK allows me to make 'sticky' services where I can get the last message that service produced upon subscribing.

I am thinking of doing something similar in a generic way: making it possible to hold a snapshot of some object graph, probably in JSON, with a version token, and then for initial loads, just being able to fetch those and turn them into CoreData object graphs locally.

Question is does this strategy make sense or should I hold my nose and write pyramid of doom code with nested queries? (Don't suggest using CoreData syncing as that has been deprecated.)

Answer 1

Your question is a bit old, so you probably already moved on from this, but I figured I'd suggest an option.

You could create a record type called Data in the Public database in your CloudKit container. Within Data, you could have a field named structure that is a String (or a CKAsset if you wanted to attach a JSON file).

Then on every app load, you query the public database and pull down the structure string that has your classes definitions and use it how you like. Since it's in the public database, all your users would have access to it. Good luck!