How to : Detect if a observable has not emitted any events for specific time in RxSwift

Question

New to rxSwift and trying to learn a somewhat simple function. When .timeout is used on an observable sequence it will return an error message Unhandled error happened: Sequence timeout. if one of the observables in the sequence didn't emit an event.

This is my attempt at handling an observable no longer receiving events, if there is a better way to achieve this please suggest it!

How can I fire off an alert if the .timeout operator returns an error message.

.timeout information: Summary

Applies a timeout policy for each element in the observable sequence. If the next element isn’t received within the specified timeout duration starting from its predecessor, a TimeoutError is propagated to the observer. Declaration

dueTime
Maximum duration between values before a timeout occurs.

scheduler Scheduler to run the timeout timer on.

Returns

An observable sequence with a RxError.timeout in case of a timeout.

Code :

    Observable.combineLatest(currentUser, opponent, game)
      .timeout(3, scheduler: MainScheduler.instance)


      .subscribe(onNext: { (arg) -> Void in

        let (currentUser, opponent, game) = arg

        if game.isPlayersTurn(currentUser) {
          self._turnState.onNext(.yourTurn)
        } else if game.isPlayersTurn(opponent) {
          self._turnState.onNext(.theirTurn)
        } else if game.isTie() {
          self._turnState.onNext(.tie)
        } else if game.gameData.winner == currentUser.userId {
          self._turnState.onNext(.win(opponentWon: false))
        } else if game.gameData.winner == opponent.userId {
          self._turnState.onNext(.win(opponentWon: true))
        }
      })
      .disposed(by: disposeBag)
  }

Answer 1

Doing some documentation research I found rxSwift's onError: handler.

This will fire off upon receiving an errorEvent, from there I can run a function onError: {err in errorAlert(); print("error \(err)")} That solves the problem.