ASP.NET Find Control Recursively

Sometimes we need to get a control instance inside a page. Looking up each control recursively is the easiest way:

using System;
using System.Collections.Generic;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

public partial class _Default : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        LoginInfoUserControl loginControl = FindControl<LoginInfoUserControl>(this.Page, "ucLogin");
    }

    public static T FindControl<T>(Control root, string controlID) where T : class
    {
        if (root is T && root.ID == controlID)
        {
            return root as T;
        }
        foreach (Control control in root.Controls)
        {
            T foundControl = FindControl<T>(control, controlID);
            if (foundControl != null)
            {
                return foundControl;
            }
        }
        return null;
    }
}