How to handle navigation with observables using Rx-MVVM-C - swift

Question

Hello I am trying to do a project with RxSwift and I am stuck trying to do in a properly way the connection between the Coordinator and the ViewModel.
Goal
Using observables, the Coordinator receives and event (in that case, when a row has been tapped) then does whatever.
Scenario
Giving a Post (String)
typealias Post = String
I have the following Coordinator:
class Coordinator {
func start() {
let selectedPostObservable = PublishSubject<Post>()
let viewController = ViewController()
let viewModel = ViewModel()
viewController.viewModel = viewModel
selectedPostObservable.subscribe { post in
//Do whatever
}
}
}
The selectedPostObservable is what I don't know how to connect it in a "clean" way with the viewModel.
As ViewModel:
class ViewModel {
struct Input {
let selectedIndexPath: Observable<IndexPath>
}
struct Output {
//UI Outputs
}
func transform(input: Input) -> Output {
let posts: [Post] = Observable.just(["1", "2", "3"])
//Connect with selectedindex
let result = input.selectedIndexPath
.withLatestFrom(posts) { $1[$0.row] }
.asDriver(onErrorJustReturn: nil)
return Output()
}
}
The result variable is what I should connect with selectedPostObservable.
And the ViewController (although I think is not relevant for the question):
class ViewController: UIViewController {
//...
var viewModel: ViewModel!
var tableView: UITableView!
//...
func bindViewModel() {
let input = ViewModel.Input(selectedIndexPath: tableView.rx.itemSelected.asObservable())
viewModel.transform(input: input)
}
}
Thank you so much.

Answer 1

Working with the structure you are starting with, I would put the PublishSubject in the ViewModel class instead of the Coordinator. Then something like this:
class ViewModel {
struct Input {
let selectedIndexPath: Observable<IndexPath>
}
struct Output {
//UI Outputs
}
let selectedPost = PublishSubject<Post>()
let bag = DisposeBag()
func transform(input: Input) -> Output {
let posts: [Post] = Observable.just(["1", "2", "3"])
//Connect with selectedindex
input.selectedIndexPath
.withLatestFrom(posts) { $1[$0.row] }
.bind(to: selectedPost)
.disposed(by: bag)
return Output()
}
}
class Coordinator {
func start() {
let viewController = ViewController()
let viewModel = ViewModel()
viewController.viewModel = viewModel
viewModel.selectedPost.subscribe { post in
//Do whatever
}
.disposed(by: viewModel.bag)
}
}