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The Easiest Core Data

Over the past months I spent a lot of time on Core Data, I had to deal with a project with a lot of legacy code, Core Data horros and multithreading violations. Core Data is hard, at times it can be frustrating and confusing. For this reasons, I decided to come up with a refined solution for a super simple design. The aim was to write a minimalistic, thread-safe, non-boilerplate and super easy to use version of Active Record on Core Data, that is actually all you need for doing Core Data in the 95% of the cases. The iterations were a few and I reconsidered my solution multiple times until I finally got where I wanted.

So… here it is. Let me introduce Skiathos and Skopelos. Skiathos is the Objective-C version, while Skopelos is the Swifty one. They are available as CocoaPods. The names come from 2 islands in Greece where I spent my 2016 summer holidays and found the inspiration to refine the final versions.

General notes

This component aims to have an extremely easy interface to introduce Core Data into your app with almost zero effort.

The design introduced here involves a few main components:

  • CoreDataStack
  • AppStateReactor
  • DALService (Data Access Layer)

CoreDataStack

If you have experience with Core Data, you might know that creating a stack is an annoying process full of pitfalls. This component is responsible for the creation of the stack (in terms of chain of managed object contexts) using the design described here by Marcus Zarra.

https://s3.amazonaws.com/albertodebortoli.github.com/images/coredata/coredatastack.png" width="849" height="238">

An important difference from Magical Record, or other third-party libraries, is that the savings always go in one direction, from slaves down (or up?) to the persistent store. Other components allow you to create slaves that have the private context as parent and this causes the main context not to be updated or to be updated via notifications to merge the context. The main context should be the source of truth and it is tied the UI: having a much simpler approach helps to create a system easier to reason about.

written in active record, core data, ios, persistence Read on →