c# relaxed boolean cast

/// <summary>
/// Parse strings into true or false bools using relaxed parsing rules
/// </summary>
public static class BoolParser
{
  /// <summary>
  /// Get the boolean value for this string
  /// </summary>
  public static bool GetValue(string value, bool defaultValue)
  {
    var result = IsTrue(value, defaultValue);
    if (result == null) return defaultValue;
    return (bool) result;
  }

  public static bool? GetValue(string value)
  {
    return IsTrue(value);
  }

  /// <summary>
  /// Determine whether the string is equal to True
  /// </summary>
  private static bool? IsTrue(string value, bool? defaultValue = null)
  {
    try
    {
      if (value == null)
      {
        return defaultValue;
      }

      value = value.Trim().ToLower();

      switch (value)
      {
        case "true":
        case "t":
        case "1":
        case "yes":
        case "yeah":
        case "yup":
        case "y":
          return true;
        case "false":
        case "f":
        case "0":
        case "no":
        case "nope":
        case "n":
          return false;
        default:
          return defaultValue;
      }
    }
    catch
    {
      return defaultValue;
    }
  }
}