(This model naming is more suitable for mobile app projects.)

The Domain is basically what is the App about and what it can do (Entities, UseCase etc.) It does not depend on UIKit or any persistence framework, and it doesn't have implementations apart from entities Domain contains Protocols of eatch platform so there is no dependency between the platforms and they can work with eachother through the protocols.

The Platform is a concrete implementation of the Domain in a specific platform like iOS. It does hide all implementation details.

Provide an implementation of DataBase protocols defined in domain.

Provide an implementation of features useCase protocols.

Works with database protocols and Provide an implementation of suggestion useCase protocols. so the algorithm of creating playlists has no dependency to the dataBase platform

works only with playable models and provide infos about the AudioPlayerManager.

Application is responsible for delivering information to the user and handling user input. It can be implemented with any delivery pattern e.g (in Playor is MVVMC). This is the place for UIViews and UIViewControllers. As you will see from the app, ViewControllers are completely independent of the Platform. The only responsibility of a view controller is to "bind" the UI to the Domain to make things happen.