我如何告诉RxSwift无论成功或失败都要做某事

Question

I have a method on a class that calls a service, it uses the response from that service to pass an ID into another service, making a second call.

If either of these fail or when the sequence is completed, I'd like to call another function self.showHomeScene()

   private func getPropsForHomeScene() {

        profileService.fetchCurrentUser()
            .map { $0.company }
            .flatMap(companyService.fetchCompany)
            .distinctUntilChanged()
            .subscribe(onNext: { company in
                 self.showHomeScene()
            }, onError: { err in
                print(err.localizedDescription)
            }).disposed(by: disposeBag)
    }

Currently I do it in the subscribe block, however this does not get called in the event of an error. It's important this action is called after the first 2 operations.

Answer 1

For this and questions like it, you want to outline all the reasons to perform this output and make them inputs to the stream in question.

You want the showHomeScene() method to be called when the first call fails or when the second call emits a stop event.

private func getPropsForHomeScene() {
    let currentUser = profileService.fetchCurrentUser()
        .share(replay: 1)

    let company = currentUser
        .map { $0.company }
        .flatMap { companyService.fetchCompany($0) }

    let currentUserFailed = currentUser
        .materialize()
        .map { $0.error }
        .filter { $0 != nil }
        .map { _ in }

    let companyStopped = company
        .materialize()
        .filter { $0.isStopEvent }
        .map { _ in }

    Observable.merge(currentUserFailed, companyStopped)
        .subscribe(onNext: {
            self.showHomeScene()
        })
        .disposed(by: disposeBag)
}

I notice you don't do anything with the actual company or current user objects that get fetched. That doesn't affect this subscribe of course but I expect you will want to subscribe to currentUser and company to do something with them as well. In that case, you should put a share on the company stream just like it's already on the currentUser stream.