gistfile1.cs

private void LoadSpotTiles()
{
    _referenceDataRepository.GetCurrencyPairsStream()
        .ObserveOn(_concurrencyService.Dispatcher)
        .SubscribeOn(_concurrencyService.TaskPool)
        .Subscribe(
            currencyPairs => currencyPairs.ForEach(HandleCurrencyPairUpdate),
            error => _log.Error("Failed to get currencies", error));
}

private void HandleCurrencyPairUpdate(ICurrencyPairUpdate update)
{
    var spotTileViewModel = SpotTiles.FirstOrDefault(stvm => stvm.CurrencyPair == update.CurrencyPair.Symbol);
    if (update.UpdateType == UpdateType.Add)
    {
        if (spotTileViewModel != null)
        {
            // we already have a tile for this currency pair
            return;
        }

        var spotTile = _spotTileFactory(update.CurrencyPair, _config.Config.SubscriptionMode);
        SpotTiles.Add(spotTile);
    }
    else
    {
        if (spotTileViewModel != null)
        {
            SpotTiles.Remove(spotTileViewModel);
            spotTileViewModel.Dispose();
        }
    }
}