Here is the basic idea:
   private void editorForWidget_EditCompleted(object sender, Editor.EditEventArgs e)
        {
      
       ....            
          
                     if (e.Action == Editor.EditAction.Add)
                     {
                          foreach (Editor.Change change in e.Edits)
                          {
                              if (change.Layer != null && change.Layer is FeatureLayer && change.Graphic != null)
                              {
                                  
                               Graphic feat = change.Graphic;
                   
                                feat.Attributes["UniqueID"] = maxID + 1;
                                feat.Attributes["POINT_XCoord"] = Math.Round(feat.Geometry.Extent.GetCenter().X,2);
                                feat.Attributes["POINT_YCoord"] = Math.Round(feat.Geometry.Extent.GetCenter().Y,2);
                                feat.Attributtes["Name"] = "unknown";
                                   ...
                  
                                FeatureLayer featureLayer = change.Layer as FeatureLayer;
                                FDForm.ApplyChanges();                                       //form in xaml page
                                ShowAttributeForm(featureLayer, feat);
                                maxID = maxID + 1;
                                break;
                                }
                             }
                        }
          }