A simple implementation of UITableViewDescriptor.

UITableViewDescriptor.swift

class UITableViewDescriptor: NSObject {
    var tableView: UITableView? {
        didSet {
            configureBindings()
        }
    }
    
    private var dataSource: UITableViewDiffableDataSource<Int, AnyHashable>!
    private var sections = [UITableViewSection]()
    private let sectionsPublisher: AnyPublisher<[UITableViewSection], Never>
    private var subscriptions = Set<AnyCancellable>()
        
    convenience init(sections: [UITableViewSection]) {
        self.init(sections: Just(sections).eraseToAnyPublisher())
    }
    
    init<T: Publisher>(sections: T) where T.Output == [UITableViewSection], T.Failure == Never {
        self.sectionsPublisher = sections.eraseToAnyPublisher()
    }
    
    func updateSnapshot() {
        var snapshot = NSDiffableDataSourceSnapshot<Int, AnyHashable>()
        snapshot.appendSections(sections.map { $0.sectionIndex })
        
        for section in sections {
            snapshot.appendItems(section.items, toSection: section.sectionIndex)
        }
        
        dataSource.apply(snapshot, animatingDifferences: true)
    }
    
    private func configureBindings() {
        guard let tableView = self.tableView else { return }
        
        dataSource = UITableViewDiffableDataSource<Int, AnyHashable>(
            tableView: tableView,
            cellProvider: {(tableView, indexPath, data) in
                self.sections[indexPath.section].cellForRow(in: tableView, indexPath: indexPath)
            }
        )
        
        tableView.dataSource = self.dataSource
                
        sectionsPublisher.sink {
            self.sections = $0
            self.sections.enumerated().forEach { $1.attach(to: self, sectionIndex: $0) }
            self.updateSnapshot()
        }.store(in: &subscriptions)
    }
}

extension UITableViewDescriptor: UITableViewDelegate {
    func numberOfSections(in tableView: UITableView) -> Int {
        sections.count
    }
    
    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        sections[section].numberOfRows()
    }
}