SwiftUI MVVM architecture - Dao

WordsetCategoriesDao.swift

class WordsetCategoryDao: BaseDao<WordsetCategoryDTO, WordsetCategory>, WordsetCategoryDaoProtocol {
    
    func update(_ entities: [WordsetCategoryDTO]) -> Future<UpdateResult, Error> {
        
        Future { [weak self] promise in

            let context = self?.storage.backgroundContext
            context.perform {
                switch Self.update(context: context, entities) {
                case .success(let change):
                    self?.storage.saveContext(context)
                    promise(.success(change))
                case .failure(let error):
                    promise(.failure(error))
                }
            }
        }
    }

   // MARK: - Mapping DTO to managed objects

    override func encode(entity e: WordsetCategoryDTO, into obj: inout WordsetCategory) {
        obj.categoryId = String(e.categoryId)
        obj.foreignName = e.foreignName
        obj.nativeName = e.nativeName
    }  
    
    override func decode(object o: WordsetCategory) -> WordsetCategoryDTO {
        WordsetCategoryDTO(categoryId: o.id, foreignName: o.foreignName!, nativeName: o.nativeName!, image: nil)
    }
}