Explanation
Parent's viewModel hold the reference of their children's viewModel, which also will be source of turth. Leverage the Combine framework to subscribe to the children's vm property changed then assign back to current vm's property.
class MainMovieViewModel: ObservableObject {
@Published var selectedMovie: Movie
@Published var destinationRouter: MyRouter? = nil
private var moviesList: [Movie] = []
var cancellable: Set<AnyCancellable> = []
// Source of truth for the child view model, the parent's vm hold the reference
var secondViewModel: MovieDetailsViewModel?
init(selectedMovie: Movie) {
self.selectedMovie = selectedMovie
self.moviesList = moviesListData
self.secondViewModel = MovieDetailsViewModel(selectedAccount: selectedMovie)
}
func prepareRouteToDetail() {
// Before initiating the route, generate the needed data for the viewModel
secondViewModel = MovieDetailsViewModel(selectedAccount: selectedMovie)
// Suscribe to the child vm's selectedMovie. Whenever the value is change in child's view. We assign back to current vm.
secondViewModel?.$selectedMovie
.sink(receiveValue: { movie in
self.selectedMovie = movie
})
.store(in: &cancellable)
if let secondViewModel = secondViewModel {
// initate the route
destinationRouter = .movieDetail(secondViewModel)
}
}
func setMovie(_ movie: Movie) {
selectedMovie = movie
}
// Creating the destination view base on corresponding scenario.
@ViewBuilder
func routeToDestination() -> some View {
if let destinationRouter = destinationRouter {
switch destinationRouter {
case .movieDetail(let secondViewModel):
MovieDetailsView(vm: secondViewModel)
}
}
}
func resetRoute() {
destinationRouter = nil
secondViewModel = nil
}
}