Retrieving Elements Stored in a SelectionFilterElement

Building on this previous post, here is how to retrieve elements that are stored in a SelectionFilterElement. After getting the elements, the code below shows how to select them in the Revit UI.

public void GetSelectionFilterElements()
{
    Document doc = this.ActiveUIDocument.Document;
    UIDocument uidoc = new UIDocument(doc);

    // Get the SelectionFilterElement named "My Selection Filter" with this LINQ statement
    SelectionFilterElement filter = (from f in new FilteredElementCollector(doc)
        .OfClass(typeof(SelectionFilterElement))
        .Cast<SelectionFilterElement>()
        where f.Name == "My Selection Filter" select f).First();

    // Get ids of elements in the filter
    ICollection<ElementId> filterIds = filter.GetElementIds();

    // Report # of elements to user
    TaskDialog.Show("Elements in filter", filterIds.Count.ToString());
    // ToString() must be used here because Count returns an integer and TaskDialog.Show requires a string
    // This hasn't been needed in other examples because when you concatenate a string with an integer
    // the whole thing automatically becomes a string. So ToString() would not be needed if I did:
    // "Number of elements is " + fitlerIds.Count

    // Now select the elements in "My Selection Filter" in the Revit UI
    // Create a SelElemenSet object
    SelElementSet selSet = SelElementSet.Create();
    foreach (ElementId id in filterIds) // loop through the elements in the filter
    {
        Element e = doc.GetElement(id); // get the element for each id
        selSet.Add(e); // add the element to the SelElementSet
    }
    // Use the SelElementSet to set the elements shown as selected in the Revit UI
    uidoc.Selection.Elements = selSet; 
    // Refresh the active view so that the change in selection higlighting is shown
    uidoc.RefreshActiveView();
}