Medium blogpost snippet

NetworkToggleStorage.swift

import RxSwift

final class NetworkToggleStorage: ToggleStorage {

    // MARK: - Properties

    private var value: Bool

    // MARK: - Initializers

    init(value: Bool) {
        self.value = value
    }

    // MARK: - Public

    func read() -> Observable<Bool> {
        return Observable.just(value)
            .delay(3, scheduler: MainScheduler.instance)
    }

    func save(value: Bool) -> Observable<Void> {
        let simulateError = shouldFail()

        return Observable.just(())
            .delay(1, scheduler: MainScheduler.instance)
            .flatMap { _ -> Observable<Void> in
                if simulateError {
                    return .error(NetworkToggleStorageError.savingError)
                } else {
                    return .just()
                }
            }
            .do(onNext: { [weak self] in
                if !simulateError {
                    self?.value = value // update saved value
                }
            })
    }

    // MARK: - Private

    private var count = 0

    private func shouldFail() -> Bool {
        count += 1
        return count % 3 == 0 // fail every 3 saves
    }

}