Core Data Background Thread Returning Inserted NSManagedObject - swift

Question

In my app I am using a NSPersistantContainer with two NSManagedObjectContexts (viewContext & background context). All my read operations are performed on view context, while all my write operations are performed on the background context (shown below).
Creating a new Animal class
class func new(_ eid: String) {
//Create Animal Entity
let container = CoreDataService.persistentContainer
container.performBackgroundTask { (context) in
let mo = Animal(context: context)
mo.eid = eid
mo.lastModified = Date()
mo.purchaseDate = Date()
mo.uuid = UUID()
do {
try context.save()
}
catch let error {
print(error)
}
}
}
The problem I am having is I need to return the newly created NSManagedObject (Animal) back to the manager class, where the Animal.new(eid) was called, to be used to show the object properties.
I have experimented with using a completion handler, but had issues returning the value, as was using a background NSManagedObject in the main thread.
Using possible new function
Animal.new(eid) { (animal) in
if let animal = animal {
}
What is the best approach for returning a newly created NSManagedObject, created in a background context?

Answer 1

What I do is to keep my CoreData managed objects within my CoreDataManager class, not exposing them out to the rest of my framework. So methods that are to create one or more managed objects would accept the data as an unmanaged object, and then create the managed object but not return it (as callers already have the unmanaged object). When fetching from the CoreDataManager, I'd create and populate a unmanaged object(s) and return that.
Now part of why I do this is because I'm using CoreData in a framework, such that I'd never want to hand a managed object to a client app of my framework. But it also solves other problems like the one you described.
(When I write apps, I use Realm, and those objects can go straight to app's UI classes because Realm is so much easier to, erm, manage. :)