DataForm: Collapsible Groups

TKDataForm supports expand/collpase behavior for its property groups when the group's header is tapped. To allow exapnding and collapsing groups, you should implement dataForm:updateGroupView:forGroupAtIndex: of TKDataFormDelegate and set the collapsible property of the group view:

public override void UpdateGroupView (TKDataForm dataForm, TKEntityPropertyGroupView groupView, uint groupIndex)
{
    groupView.Collapsible = true;
    groupView.TitleView.Style.SeparatorColor = new TKSolidFill (new UIColor (0.784f, 0.780f, 0.8f, 1.0f));
}