public new RealtimeFeatureClass GetFeatureClass()

{
  // Note: call within QueuedTask.Run()
  {
    //Must be called on the feature class
    using var rfc = streamLayer.GetFeatureClass();
    rfc.Truncate();
  }
}

{
  // Note: call within QueuedTask.Run()
  {
    //query filter can be null to search and retrieve all rows
    //true means recycling cursor
    using (var rc = streamLayer.SearchAndSubscribe(qfilter, true))
    {
      //waiting for new features to be streamed
      //default is no cancellation
      while (rc.WaitForRowsAsync().Result)
      {
        while (rc.MoveNext())
        {
          using (var row = rc.Current)
          {
            //determine the origin of the row event
            switch (row.GetRowSource())
            {
              case RealtimeRowSource.PreExisting:
                //pre-existing row at the time of subscribe
                continue;
              case RealtimeRowSource.EventInsert:
                //row was inserted after subscribe
                continue;
              case RealtimeRowSource.EventDelete:
                //row was deleted after subscribe
                continue;
            }
          }
        }
      }
    }//row cursor is disposed. row cursor is unsubscribed

    //....or....
    //Use the feature class instead of the layer
    using var rfc = streamLayer.GetFeatureClass();
    //non-recycling cursor - 2nd param "false"
    using (RealtimeCursor rc = rfc.SearchAndSubscribe(qfilter, false))
    {
      //waiting for new features to be streamed
      //default is no cancellation
      while (rc.WaitForRowsAsync().Result)
      {
        //etc
      }
    }
  }
}

{
  // Note: call within QueuedTask.Run()
  {
    //Recycling cursor - 2nd param "true"
    //or streamLayer.Subscribe(qfilter, true) to just subscribe
    using (var rc = streamLayer.SearchAndSubscribe(qfilter, true))
    {
      //auto-cancel after 20 seconds
      var cancel = new CancellationTokenSource(new TimeSpan(0, 0, 20));
      //catch TaskCanceledException
      try
      {
        while (rc.WaitForRowsAsync(cancel.Token).Result)
        {
          //check for row events
          while (rc.MoveNext())
          {
            using var row = rc.Current;
            //etc
          }
        }
      }
      catch (TaskCanceledException)
      {
        //Handle cancellation as needed
      }
      cancel.Dispose();
    }
  }
}

{
  // Note: call within QueuedTask.Run()
  {
    using var rfc = streamLayer.GetFeatureClass();
    using var rfc_def = rfc.GetDefinition();
    if (rfc_def.HasTrackIDField())
    {
      //Track aware
    }
  }
}

{
  // Note: call within QueuedTask.Run()
  {
    using (var rfc = streamLayer.GetFeatureClass())
    using (var rfc_def = rfc.GetDefinition())
    {
      if (rfc_def.HasTrackIDField())
      {
        var fld_name = rfc_def.GetTrackIDField();

      }
    }
  }
}