inventory and assembly search in c#

@operator

i am searching both categories at the same time inventory items and assembly items, i am getting a record back. i am trying to loop through the record but i am getting an error. is there a way to check first what i am casting to before i loop or i need to seperate the search?

var itemSearch = new ItemSearch();
            var itemSearchBasic = new ItemSearchBasic();

            /////////////////////type of item///////////////////////////////////////////
            var sEmSfield = new SearchEnumMultiSelectField();

            var assInventory = new string[] { "_assembly", "_inventoryItem" };

            sEmSfield.searchValue = assInventory;
            sEmSfield.@operator = SearchEnumMultiSelectFieldOperator.anyOf;
            sEmSfield.operatorSpecified = true;

            itemSearchBasic.type = sEmSfield;

           // this is optional- on the first run for sure don't use it.