How to convert string to TitleCase

public static String TitleCaseString(String s)

{

   if (s == null) return s;

   String[] words = s.Split(' ');

   for (int i = 0; i < words.Length; i++)

   {

     if (words[i].Length == 0) continue;

     Char firstChar = Char.ToUpper(words[i][0]);

     String rest = "";

     if (words[i].Length > 1)

     {

      rest = words[i].Substring(1).ToLower();

     }

     words[i] = firstChar + rest;

   }

    return String.Join(" ", words);

}