Unity InputFiled 输入限制

只允许InputFiled输入固定字符：

namespace LastZero.Utility
{
    public static class InputFiledLimit
    {
        /// <summary>
        /// 输入限制
        /// </summary>
        /// <param name="ipt">输入框</param>
        /// <param name="limitStr">可输入的字符</param>
        public static void Limit(this InputField ipt, string limitStr)
        {
            ipt.onValueChanged.AddListener(v => {
                if (ipt.text.Equals(string.Empty))
                    return;
                string lastChar = (ipt.text.ToCharArray()[ipt.text.Length - 1]).ToString();
                if (ipt.text.Remove(ipt.text.Length - 1).Contains(lastChar) || !limitStr.Contains(lastChar))//最后一个字符与前面重复 或者 不是包含于1234
                {
                    ipt.text = ipt.text.Remove(ipt.text.Length - 1);
                }
            });
        }
    }
}