public static DateTime UnixTimeStampToDateTime( double unixTimeStamp ){    // Unix timestamp is seconds past epoch    System.DateTime dtDateTime = new DateTime(1970,1,1,0,0,0,0,System.DateTimeKind.Utc);    dtDateTime = dtDateTime.AddSeconds( unixTimeStamp ).ToLocalTime();    return dtDateTime;}

https://stackoverflow.com/questions/...and-vice-versa