You need to iterate using
DataRow inside a Datatable.
You cannot use
SPListItem to iterate inside a datatable as its incorrect.
The object model to use Datatable is
DataTable -> DataRowCollection -> DataRow where you use the DataRow to look for contents inside a column of a row
Code would be somewhat as below:
foreach(DataRow row in results.Rows)
//if you want to use column name, try the below line of code.
var title = Convert.ToString(row["Title"]);
//if you want to use index, try the below line of code.
//var title = Convert.ToString(row);