C# TextBox 新增文本并定位光标

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace HS_INSURANCE_PLATFORM_FORM.BaseTool
{
    public class ControlHelper
    {
        //定义一个用于保存静态变量的实例
        private static ControlHelper instance = null;
        //定义一个保证线程同步的标识
        private static readonly object locker = new object();
        //构造函数为私有，使外界不能创建该类的实例
        private ControlHelper() { }
        public static ControlHelper Instance
        {
            get
            {
                if (instance == null)
                {
                    lock (locker)
                    {
                        if (instance == null) instance = new ControlHelper();
                    }
                }
                return instance;
            }
        }

        public void TxbWriteValue(TextBox txtContent, string value)
        {
            Console.WriteLine(value);
            txtContent.Text += value + "\r\n\r\n";
            txtContent.Focus();//获取焦点
            txtContent.Select(txtContent.TextLength, 0);//光标定位到文本最后
            txtContent.ScrollToCaret();//滚动到光标处
        }

    }
}