ArcGIS Pro 2.7 API Reference Guide
AddGeometries Method
Example 

ArcGIS.Core.Geometry Namespace > GeometryBagBuilder Class : AddGeometries Method
The list of geometries to add.
Adds the given list of geometries to the end of the list of geometries in this GeometryBag.
Syntax
public void AddGeometries( 
   IEnumerable<Geometry> geometries
)
Public Sub AddGeometries( _
   ByVal geometries As IEnumerable(Of Geometry) _
) 

Parameters

geometries
The list of geometries to add.
Exceptions
ExceptionDescription
This method or property must be called within the lambda passed to QueuedTask.Run.
geometries is null.
A geometry in geometries is null. You cannot add a null geometry into GeometryBag.
A geometry in geometries is GeometryBag. You cannot add a GeometryBag to another GeometryBag.
Remarks
An Envelope is converted to a Polygon when it is inserted into a GeometryBag. As a result, when retrieving an Envelope from a GeometryBag, it will be a Polygon.
Example
MapPoint point = MapPointBuilder.CreateMapPoint(10, 20);
List<Coordinate2D> coords = new List<Coordinate2D>() { new Coordinate2D(50, 60), new Coordinate2D(-120, -70), new Coordinate2D(40, 60) };
Multipoint multipoint = MultipointBuilder.CreateMultipoint(coords, SpatialReferences.WebMercator);
Polyline polyline = PolylineBuilder.CreatePolyline(coords);

string json = "{\"rings\":[[[0,0],[0,1],[1,1],[1,0],[0,0]],[[3,0],[3,1],[4,1],[4,0],[3,0]]]}";
Polygon polygon = PolygonBuilder.FromJson(json);

var geometries = new List<Geometry>() { point, multipoint, polyline, polygon };

// Builder constructors need to run on the MCT.
ArcGIS.Desktop.Framework.Threading.Tasks.QueuedTask.Run(() =>
{
  using (var builder = new GeometryBagBuilder(SpatialReferences.WGS84))
  {
    // builder.CountGeometries = 0

    builder.AddGeometries(geometries);
    // builder.CountGeometries = 4

    GeometryBag geomBag = builder.ToGeometry();
    // bag.PartCount = 4    (point, multipoint, polyline, polygon)

    geometries = new List<Geometry>() { point, polyline };
    builder.InsertGeometries(1, geometries);
    // builder.CountGeometries = 6
    geomBag = builder.ToGeometry();
    // bag.PartCount = 6    (point, point, polyline, multipoint, polyline, polygon)
  }
});
Requirements

Target Platforms: Windows 10, Windows 8.1

See Also

Reference

GeometryBagBuilder Class
GeometryBagBuilder Members