限制字符串的长度不大于指定值

private string RestrictInputContentLength(string value, int length = 16)
{
    string newValue = string.Empty;
    int newLength = 0;
    foreach (var v in value)
    {
        int l = System.Text.Encoding.UTF8.GetBytes(v.ToString()).Length;
        l = Mathf.Min(l, 2);
        if (newLength + l <= length)
        {
            newValue += v;
            newLength += l;
        }
        else
        {
            break;
        }
    }
    return newValue;
}