Dynamically filter results with RxSwift and Realm

Question

I have a very simple project, where I want to dynamically filter content in UITableView regarding pressed index in UISegmentedControl. I'm using MVVM with RxSwift, Realm and RxDataSources. So my problem, that if I want to update content in UITableView I need to create 'special' DisposeBag, only for that purposes, and on each selection in UISegmentedControl nil it and create again. Only in this case, if I'm understand right, subscription is re-newed, and UITableView displays new results from Realm. So is there any better way to do such operation? Without subscribing every time, when I switch tab in UISegmentedControl. Here's my code:

//ViewController
class MyViewController : UIViewController {

  //MARK: - Props
  @IBOutlet weak var tableView: UITableView!
  @IBOutlet weak var segmentedControl: UISegmentedControl!

  let dataSource = RxTableViewSectionedReloadDataSource<ItemsSection>()
  let disposeBag = DisposeBag()

  var tableViewBag: DisposeBag!
  var viewModel: MyViewModel = MyViewModel()

  //MARK: - View lifecycle
  override func viewDidLoad() {
    super.viewDidLoad()
    self.setupRxTableView()
  }

  //MARK: - Setup observables
  fileprivate func setupRxTableView() {
    dataSource.configureCell = { ds, tv, ip, item in
      let cell = tv.dequeueReusableCell(withIdentifier: "ItemCell") as! ItemTableViewCell
      return cell
    }

    bindDataSource()

    segmentedControl.rx.value.asDriver()
      .drive(onNext: {[weak self] index in
        guard let sSelf = self else { return }
        switch index {
        case 1:
          sSelf.bindDataSource(filter: .active)
        case 2:
          sSelf.bindDataSource(filter: .groups)
        default:
          sSelf.bindDataSource()
        }
      }).disposed(by: disposeBag)
  }

  private func bindDataSource(filter: Filter = .all) {
    tableViewBag = nil
    tableViewBag = DisposeBag()
    viewModel.populateApplying(filter: filter)
      }).bind(to: self.tableView.rx.items(dataSource: dataSource))
      .disposed(by: tableViewBag)
  }
}

//ViewModel
   class MyViewModel {
      func populateApplying(filter: Filter) -> Observable<[ItemsSection]> {
       return Observable.create { [weak self] observable -> Disposable in
         guard let sSelf = self else { return Disposables.create() }
         let realm = try! Realm()
         var items = realm.objects(Item.self).sorted(byKeyPath: "date", ascending: false)
         if let predicate = filter.makePredicate() { items = items.filter(predicate) }
         let section = [ItemsSection(model: "", items: Array(items))]
         observable.onNext(section)

         sSelf.itemsToken = items.addNotificationBlock { changes  in
           switch changes {
             case .update(_, _, _, _):
             let section = [ItemsSection(model: "", items: Array(items))]
             observable.onNext(section)
             default: break
          }
        }
        return Disposables.create()
       }
     }
   }

Answer 1

Don't recall if this is breaking MVVM off the top of my head, but would Variable not be what you're looking for?

Variable<[TableData]> data = new Variable<[TableData]>([])

func applyFilter(filter: Predicate){
  data.value = items.filter(predicate) //Any change to to the value will cause the table to reload
}

and somewhere in the viewController

viewModel.data.rx.asDriver().drive
        (tableView.rx.items(cellIdentifier: "ItemCell", cellType: ItemTableViewCell.self))
{ row, data, cell in

    //initialize cells with data
}