public static FieldDescription CreateDomainField( 
   string name,
   DomainDescription domainDescription
)

public void CreateTableSnippet(Geodatabase geodatabase, CodedValueDomain inspectionResultsDomain)
{
  // Create a PoleInspection table with the following fields
  //  GlobalID
  //  ObjectID
  //  InspectionDate (date)
  //  InspectionResults (pre-existing InspectionResults coded value domain)
  //  InspectionNotes (string)

  // This static helper routine creates a FieldDescription for a GlobalID field with default values
  FieldDescription globalIDFieldDescription = FieldDescription.CreateGlobalIDField();

  // This static helper routine creates a FieldDescription for an ObjectID field with default values
  FieldDescription objectIDFieldDescription = FieldDescription.CreateObjectIDField();

  // Create a FieldDescription for the InspectionDate field
  FieldDescription inspectionDateFieldDescription = new FieldDescription("InspectionDate", FieldType.Date)
  {
    AliasName = "Inspection Date"
  };

  // This static helper routine creates a FieldDescription for a Domain field (from a pre-existing domain)
  FieldDescription inspectionResultsFieldDescription = FieldDescription.CreateDomainField("InspectionResults", new CodedValueDomainDescription(inspectionResultsDomain));
  inspectionResultsFieldDescription.AliasName = "Inspection Results";

  // This static helper routine creates a FieldDescription for a string field
  FieldDescription inspectionNotesFieldDescription = FieldDescription.CreateStringField("InspectionNotes", 512);
  inspectionNotesFieldDescription.AliasName = "Inspection Notes";

  // Assemble a list of all of our field descriptions
  List<FieldDescription> fieldDescriptions = new List<FieldDescription>()
    { globalIDFieldDescription, objectIDFieldDescription, inspectionDateFieldDescription, inspectionResultsFieldDescription, inspectionNotesFieldDescription };

  // Create a TableDescription object to describe the table to create
  TableDescription tableDescription = new TableDescription("PoleInspection", fieldDescriptions);

  // Create a SchemaBuilder object
  SchemaBuilder schemaBuilder = new SchemaBuilder(geodatabase);

  // Add the creation of PoleInspection to our list of DDL tasks
  schemaBuilder.Create(tableDescription);

  // Execute the DDL
  bool success = schemaBuilder.Build();

  // Inspect error messages
  if (!success)
  {
    IReadOnlyList<string> errorMessages = schemaBuilder.ErrorMessages;
    //etc.
  }
}

public void AddFieldWithDomainSnippet(Geodatabase geodatabase)
{
  // Adding a field,'PipeType', which uses the coded value domain to the 'Pipes' FeatureClass

  //The FeatureClass to add field
  string featureClassName = "Pipes";

  SchemaBuilder schemaBuilder = new SchemaBuilder(geodatabase);

  // Create a CodedValueDomain description for water pipes
  CodedValueDomainDescription pipeDomainDescription =
    new CodedValueDomainDescription("WaterPipeTypes", FieldType.String,
    new SortedList<object, string> { { "C_1", "Copper" },
      { "S_2", "Steel" } })
    {
      SplitPolicy = SplitPolicy.Duplicate,
      MergePolicy = MergePolicy.DefaultValue
    };

  // Create a coded value domain token
  CodedValueDomainToken codedValueDomainToken = schemaBuilder.Create(pipeDomainDescription);

  // Create a new description from domain token
  CodedValueDomainDescription codedValueDomainDescription = new CodedValueDomainDescription(codedValueDomainToken);

  // Create a field named as 'PipeType' using a domain description
  FieldDescription domainFieldDescription = new FieldDescription("PipeType", FieldType.String)
  { DomainDescription = codedValueDomainDescription };

  //Retrieve existing information for 'Pipes' FeatureClass
  FeatureClassDefinition originalFeatureClassDefinition = geodatabase.GetDefinition<FeatureClassDefinition>(featureClassName);
  FeatureClassDescription originalFeatureClassDescription =
    new FeatureClassDescription(originalFeatureClassDefinition);

  // Add domain field on existing fields
  List<FieldDescription> modifiedFieldDescriptions = new List<FieldDescription>(originalFeatureClassDescription.FieldDescriptions) { domainFieldDescription };

  // Create a new description with updated fields for 'Pipes' FeatureClass 
  FeatureClassDescription featureClassDescription =
    new FeatureClassDescription(originalFeatureClassDescription.Name, modifiedFieldDescriptions,
                                   originalFeatureClassDescription.ShapeDescription);

  // Update the 'Pipes' FeatureClass with domain field
  schemaBuilder.Modify(featureClassDescription);

  // Build status
  bool buildStatus = schemaBuilder.Build();

  // Build errors
  if (!buildStatus)
  {
    IReadOnlyList<string> errors = schemaBuilder.ErrorMessages;
  }
}