ArcGIS Convert IGeometryCollection to IEnumGeometry

Question

I have a group of polylines mistakenly created with a geometry for each vertex pair. Typically they have thousands of geometries. I would like to merge the geometries (note: NOT merge features) in each feature into one geometry. To do this I am using ITopologicalOperator5.ConstructUnion. ConstructUnion takes an IEnumGeometry parameter and I have an IGeometryCollection of geometries. I can create an IEnumGeometry using a GeometryBag but ConstructUnion does not accept GeometryBags. If I use IEnumGeometry pEnum = (IEnumGeometry)pGeomCollection it throws an exception. If I use IEnumGeometry pEnum = pGeomCollection as IEnumGeometry then pEnum is null. In VB.NET Ctype(pGeomCollection, IEnumGeometry) works fine. Can anyone tell me how to convert a (C#) Geometry Collection into an IEnumGeometry?

Thanks,

John

Answer 1

The solution is to link the Geometry Bag and the Geometry Collection when they are initiated:

IGeometryBag pGeomBag = new GeometryBagClass();
pGeomBag.SpatialReference = .......

IGeometryCollection pGeomColl = new PolylineClass();
pGeomColl = (IGeometryCollection)pGeomBag;

IEnumGeometry pEnum = new EnumFeatureGeometryClass();
pEnum = (IEnumGeometry)pGeomBag;