如何识别tilelist中的选定对象？

 <mx:TileList id="tileList"
             alternatingItemColors="[#FFFFFF,#EEEEEE]"
             dataProvider="{xmlListColl}"
             itemRenderer="TileListItemRenderer"
             columnCount="3"
             columnWidth="100"
             rowCount="2"
             rowHeight="100"
             direction="horizontal"
             verticalScrollPolicy="on"/>

itemClick="somthingSelected();"

public function somthingSelected():void{
  trace( this.tileList.selectedItem.@id )
}