.onAppear {
   let predicate = #Predicate<Book> { book in
      book.author?.name == nil
   }
   let sort = SortDescriptor<Book>(\.title, order: .forward)

   let descriptor = FetchDescriptor<Book>(predicate: predicate, sortBy: [sort])
   if let list = try? dbContext.fetch(descriptor) {
      for book in list {
         print(book.title)
      }
   }
}