Medium blogpost snippet

Toggle.swift

func manage(change: Observable<Bool>) -> (value: Driver<ToggleValue>, isBusy: Driver<Bool>) {
    let storage = self.storage
    let isBusySubject = PublishSubject<Bool>()

    let isBusy = isBusySubject
        .asDriver(onErrorJustReturn: false)
        .startWith(true)

    let initialValue = storage
        .read()
        .map { ToggleValue.initial($0) }
        .catchError { Observable.just( ToggleValue.unknown($0) ) }
        .do(onNext: { _ in isBusySubject.onNext(false) })

    let valueAfterSaving = change
        .do(onNext: { _ in isBusySubject.onNext(true) })
        .flatMap { valueToSave -> Observable<ToggleValue> in
            storage
                .save(value: valueToSave)
                .map { ToggleValue.updated(valueToSave) }
                .catchErrorJustReturn(ToggleValue.fallback(!valueToSave))
        }
        .do(onNext: { _ in isBusySubject.onNext(false) })

    let value = Observable.merge(initialValue, valueAfterSaving)
        .asDriver(onErrorRecover: { Driver.just(ToggleValue.unknown($0)) })

    return (value: value, isBusy: isBusy)
}