对特定的异常进行捕获和报错
try
{
var reference = uidoc.Selection.PickObject(ObjectType.Element, "请选择您要查看的元素");
}
catch (Autodesk.Revit.Exceptions.OperationCanceledException ex)
{
TaskDialog.Show("ERROR", "未选取任何对象!");
//TaskDialog.Show("ERROR",ex.ToString());
return Result.Failed;
}