public abstract class CIMMapGrid : CIMObject, System.ComponentModel.INotifyPropertyChanged, System.Xml.Serialization.IXmlSerializable  

{
  //Note: Must be on QueuedTask.Run
  //Get the Style project items in the project
  var styleProjectItems = Project.Current?.GetItems<StyleProjectItem>();
  //Get the ArcGIS 2D Style Project Item
  var styleProjectItem =
  styleProjectItems.OfType<StyleProjectItem>().FirstOrDefault(s => s.Name == "ArcGIS 2D");
  if (styleProjectItem == null) return;
  //Get the grid style item you need
  var gridStyleItem =
  styleProjectItem.SearchSymbols(StyleItemType.Grid, "Blue Vertical Label Graticule").FirstOrDefault();
  if (gridStyleItem == null) return;
  var symbolItemName = gridStyleItem.Name;
  var girdGraticuleObject = gridStyleItem.GetObject() as CIMMapGrid;
  var cmf = mapFrame.GetDefinition() as CIMMapFrame;
  //note, if page units are _not_ inches then grid's gridline
  //lengths and offsets would need to be converted to the page units
  var mapGrids = new List<CIMMapGrid>();
  if (cmf.Grids != null)
    mapGrids.AddRange(cmf.Grids);

  switch (girdGraticuleObject)
  {
    case CIMGraticule:
      var gridGraticule = girdGraticuleObject as CIMGraticule;
      gridGraticule.Name = symbolItemName;
      gridGraticule.SetGeographicCoordinateSystem(mapFrame.Map.SpatialReference);
      //assign grid to the frame             
      mapGrids.Add(gridGraticule);

      break;
    case CIMMeasuredGrid:
      var gridMeasure = girdGraticuleObject as CIMMeasuredGrid;
      gridMeasure.Name = symbolItemName;
      gridMeasure.SetProjectedCoordinateSystem(mapFrame.Map.SpatialReference);
      //assign grid to the frame
      mapGrids.Add(gridMeasure);

      break;
    case CIMReferenceGrid:
      var gridReference = girdGraticuleObject as CIMReferenceGrid;
      gridReference.Name = symbolItemName;
      //assign grid to the frame
      mapGrids.Add(gridReference);
      break;
  }
  cmf.Grids = mapGrids.ToArray();
  mapFrame.SetDefinition(cmf);
}