Save an existing Model to a CoreData DB

I'm learning Core Data and I understand all the examples for creating a brand-new object, assigning values and saving it to the managedContext (insertNewOb开发者_Go百科jectForEntityForName). However, what if I've already created an object elsewhere (model Category)? In this case I'd want to just assign the current Context to this Model, and then save it.

What is the command/approach to take an in-memory Model, and then assign to a context so it can be saved?

If you want to use Core Data to manage your data, you'll need to:

• create an appropriate model description (.xcdatamodeld file)

• modify your model class(es) so that they inherit from NSManagedObject

• set the "Class" for each entity in your model description to one of your NSManagedObject subclasses

• add code to your app to create and manage the Core Data stack, fetch data, etc.

This is all very do-able, but I wouldn't recommend that you attempt it until you have a solid understanding of Core Data and your reasons for adopting it in your project. The lack of clarity in your question may indicate that you're not quite there yet; you might benefit from working on a small project that uses Core Data from the start.

If all you want to do is to save your data, you should know that Core Data is not the only way to do that. A much simpler approach to saving your data would be to adopt the NSCoding protocol in your data model and then use a NSKeyedArchiver to store your data. Get the full story from the Archives and Serializations Programming Guide. There are other ways to do it as well, but NSKeyedArchiver is a good place to start.

You can only save NSManagedObjects (and their subclasses) to CoreData. NSManagesObject can not be created except in the context of an NSManagedObjectContext.

So, what you're saying is confusing. Do you have a non-CoreData model object?