C# - String kürzen ohne ein Wort abzuschneiden

/// <summary>
/// Cuts the long string.
/// </summary>
/// <param name="longString">The long string.</param>
/// <param name="length">The length.</param>
/// <returns></returns>
private string CutLongString(string longString, int length)
{
    if (longString.Trim() != string.Empty)
    {
        if (longString.Length > length)
        {
            longString = longString.Substring(0, length);
            int positionLastSpace = longString.LastIndexOf(" ");
            if (positionLastSpace > -1 && positionLastSpace < length)
                longString = longString.Substring(0, positionLastSpace);

            longString += " …";
        }
    }
    return longString;
}