#RTCNA wish 6 granted! Create assemblies from groups

Here is how to create an assembly and assembly views from a group

public void assemblyFromGroup()
{
    Document doc = this.ActiveUIDocument.Document;
    UIDocument uidoc = this.ActiveUIDocument;
    
    // prompt the user to select a group
    Group group = doc.GetElement(uidoc.Selection.PickObject(ObjectType.Element)) as Group;
    
    View v3d = null;
    View partlist = null;
    View section = null;
    using (Transaction t = new Transaction(doc,"Create Assembly From Group"))
    {
        t.Start();
        
        // ungroup the group, getting the list of elements in the group
        List<ElementId> ids = group.UngroupMembers().ToList();
        
        // get the category of the first element in the group
        // a category needs to be specified when creating the assembly
        Category cat = doc.GetElement(ids.First()).Category;
        
        // create the assembly
        AssemblyInstance ai = AssemblyInstance.Create(doc, ids, cat.Id);
        
        // create the assembly views
        v3d = AssemblyViewUtils.Create3DOrthographic(doc, ai.Id);
        partlist = AssemblyViewUtils.CreatePartList(doc, ai.Id);
        section = AssemblyViewUtils.CreateDetailSection(doc, ai.Id, AssemblyDetailViewOrientation.DetailSectionA);
        t.Commit();
    }
    // activate the new views so they are visible when the command ends
    // The active view can only be changed when there is no open transaction
    uidoc.ActiveView = v3d;
    uidoc.ActiveView = partlist;
    uidoc.ActiveView = section;
}