Completion¶

Introduction¶

So when you want to send completion events for your observable chain in order to signal the consumers or observers that its time to wrap up.

But side note I have also observed that sometimes listening to onComplete events on .subscribe{} & .bind(to:) has sometimes disposed the event early and which leads to getting an .completed event from the RxObservable chain.

Model¶

public class Custom { } // Model

public protocol CustomViewModelProtocol {

    var input: CustomViewModel.Input { get }

    var output: CustomViewModel.Output { get }

}

ViewModel¶

Defining its appropriate initial states and sending observable event with specific type .Completion which would signal the observers / consumers of this ViewModel to do something after they receive specific event type.

public class CustomViewModel: ViewModellable {

    public typealias ViewStateType = ViewState<CustomState, DisplayableError, LoadingState, CustomStateEmptyState>

    let initialState = CustomState(param1: Type)
     
    let initialViewState = ViewStateType.fulfilled(initialState)
         
    let viewStateSubject = BehaviorSubject<ViewStateType>(value: initialViewState)

    let customContext = BehaviorSubject<Custom>(value: Custom())

    customContext
        .mapToVoid()
        .subscribe(onNext: viewStateSubject.onCompleted)
        .disposed(by: disposeBag)
}
            

ViewController¶

class CustomViewController: UIViewController, ViewStateResponsive {

    private let viewModel: CustomViewModelProtocol

    var viewState: Driver<CustomViewModel.ViewStateType> { viewModel.output.viewState }

    viewState
        .asObservable()
        .debug("Completed viewState")
        .subscribe(onCompleted: { [weak self] in
            self?.dismiss(animated: true)
        })
        .disposed(by: disposeBag)
}

Listening to the ViewModel while adhering to the ViewState architecture and having Input & Output as structs for easy I/O from Model = = ViewModel = = ViewController