动态添加的行未在GridView.Rows.Count中显示

protected void Page_Load(object sender, EventArgs e)
{
    if (!IsPostBack)
    {
        BindGridView();
    }
}

private void BindGridView()
{
    DataTable dt = new DataTable();
    dt.Columns.Add("Name");
    dt.Columns.Add("Age");

    // 添加初始数据
    DataRow dr = dt.NewRow();
    dr["Name"] = "John";
    dr["Age"] = 30;
    dt.Rows.Add(dr);

    GridView1.DataSource = dt;
    GridView1.DataBind();
}

protected void AddRowButton_Click(object sender, EventArgs e)
{
    DataTable dt = (DataTable)ViewState["GridData"];
    if (dt == null)
    {
        dt = new DataTable();
        dt.Columns.Add("Name");
        dt.Columns.Add("Age");
    }

    DataRow dr = dt.NewRow();
    dr["Name"] = "New User";
    dr["Age"] = 25;
    dt.Rows.Add(dr);

    ViewState["GridData"] = dt;
    GridView1.DataSource = dt;
    GridView1.DataBind();
}