The more comprehensive documentation is the CoreData programming guide (Core Data Programming Guide: What Is Core Data?):
What Is Core Data?
Core Data is a framework that you use to manage the model layer objects in your application. It provides generalized and automated solutions to common tasks associated with object life cycle and object graph management, including persistence.
Persistence is one feature, but very far from everything that CD does. The design of CD necessarily requires classes, and a Swift equivalent would likely look entirely different. That’s probably better as a community project. People generally expect Model-Layer code to be cross platform these days.
And as Xiaodi says, SwiftUI is not „official“ and has no special status whatsoever in the open source project. It’s an Apple framework for Apple‘s own platforms.