waitForResourceAndButtonTap.swift

func waitForResourceAndButtonTap(
  resource: Observable<Bool>, 
  buttonTap: Observable<Void>
) -> Observable<Bool> {
  let emitOnlyAfterResourceHasArrived = Observable
    .combineLatest(
      buttonTap,
      resource.take(1)
  )

  return emitOnlyAfterResourceHasArrived
    .withLatestFrom(resource)
}