Dim uiDoc As UIDocument = commandData.Application.ActiveUIDocument
Dim Doc As Document = uiDoc.Document
' .....
Dim coll As FilteredElementCollector = New FilteredElementCollector(Doc).OfClass(GetType(ViewSchedule))
' .....
For Each rvtViewSchedule As Autodesk.Revit.DB.ViewSchedule In coll
' .....
Dim CatName As String = New FilteredElementCollector(Doc, New ElementId(rvtViewSchedule.Id.IntegerValue)).FirstElement().Category.Name
' .....
Next