Completion

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, ViewStateBridger {

	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