CODEWITHSUNDEEP
iosswiftcore-datamagicalrecord
Livio
Livio

Reputation: 710

CoreData in-memory setup with MagicalRecord 3

Hello I'm using CoreData + MagicalRecord 3 to manage the data in my app. Until then everything was working fine, but then I realize in production than my app is freezing like hell ! So I started to investigate knowing about the fact that to not stuck the UI, it's better to have a main context and a background context and save stuff in background etc...

Nevertheless I have to question due to my setup. I use CoreData in-memory store system (for the best performance) and I don't care about storing the data on disk of my app, I'm fine with a volatile model that will be destroyed when the app is killed or in background for too long. I just want to be able to find my data from any view controller and without coupling.

So I have few questions : 1) If I would use 1 unique context, what would happen if I NEVER save it to the memory store ? For instance if I MR_createEntity then I retrieve this entity from the context and update it, is it updated everywhere or do I have to save it so it can be updated ? In other term was is the interest of saving for in-memory where you don't want to persist the data forever ?

2) If I use 1 unique context that I declare being background, if I display my screen before my data is finished to saved, the screen won't be able to find and display my data right ? Unless I use NSFetchResultController right ?

Upvotes: 0

Views: 219

Answers (1)

casademora
casademora

Reputation: 69687

1) you want to save your data even with an in memory store for a couple of reasons. First, so that you can use core data properly in the case where you might change your mind and persist your data. Second, you'll likely want to access and process some data on different threads/queues. In that case, you'll have to use Core Data's data safety mechanisms for threads/queues. The store is the lowest level at which Core Data will sync data across threads (the old way). This may be less important if you use nested contexts to sync your data (the new way). But even with nested contexts, you'll need call save in order for your changes to merge across contexts. Core Data doesn't really like it when you save to a nil store.

2) You can make and use your own context for displaying data. NSFetchedResultsController does a lot of the leg work in listening for the correct notifications and making sure you're getting very specific updates for the data you asked for in the first place. NSFRC is not always necessary, but will certainly be the easiest way to start.

Upvotes: 1

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