FRC may keep old context after core data stack is nuked

[rachelhyman]

This came up when a fetched results controller would display model objects, but then logging out, killing the app, and restarting/logging in would not display any objects despite them seemingly existing in Core Data. This was due to new objects getting inserted in a different context than the one associated with the FRC. Cc @chillpop

[seanwolter]

@rachelhyman Can you provide any additional information or sample code?
Or is someone Vokal-internal already aware of the details and fixing it?

[rachelhyman]

Steps to reproduce:

1. Set up a VOKCollectionDataSource with a collection view
2. Nuke and reset core data, then set it up again (not sure whether killing the app is integral here). In my case this happened when logging out and logging in, respectively.
3. Observe that relevant model objects exist e.g. by calling [[VOKCoreDataManager sharedInstance] countForClass:] but that nothing is being fetched or displayed. The fetched results controller of the data source is using a different context than the one objects are being added to.
4. If you follow the same steps but set up the data source again before fetching, the correct results appear.
   @seanwolter

[seanwolter]

I'm working on a collection view for the sample app. I was unable to reproduce, but I did find a lot of gnarly code in the vokcollectiondatasource. I should have a PR before the end of this week.