CoreRecord

The ActiveRecord like Core Data object management

Migrations

It's pretty common to need migrations from time to time when the App envolves over time.

CoreRecord comes with a sub-modle calle Migrations handling exactly this use-case.

Preconditions

In your CoreData model you need to add an entity called Version with only one property called migrationVersion. This is needed to check if a certain migration need to run or was already executed.

Setup

To create your migration all you need to do is to add a class in your target which implements the Migration protocol. This protocol requires you to add a migrationVersion as double. This will be stored in your CoreData model and will be used for future migrations.

This enables migrations also when someone skips an App version. All migrations with a version higher than the latest stored one will be executed.

Example:

class DeleteAllPlayers: Migration {
    static var migrationVersion: Double = 1631960191.5761361 // 18.9.2021

    static func run() -> Bool {
        Player.deleteAll()

        return true
    }
}

Execute

To execute the migration you need to register them and tell CoreRecord to run them.

The classic place for this would be the AppDelegate.application(_:didFinishLaunchingWithOptions:)

Example:

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    CoreRecord.sharedRecord.modelName = "HockeyClock"

    CoreRecord.sharedRecord.migrations
        .add(migration: DeleteAllPlayers.self)
        .runMigrations()

    return true
}