Using HookActions in custom commands
hookActionsLabel.cs
// Copyright 2012 ESRI
// 
// All rights reserved under the copyright laws of the United States
// and applicable international laws, treaties, and conventions.
// 
// You may freely redistribute and use this sample code, with or
// without modification, provided you include the original copyright
// notice and use restrictions.
// 
// See the use restrictions.
// 

using System;
using System.Drawing;
using System.Windows.Forms;
using System.Runtime.InteropServices;
using ESRI.ArcGIS.ADF.BaseClasses;
using ESRI.ArcGIS.ADF.CATIDs;
using ESRI.ArcGIS.Controls;
using ESRI.ArcGIS.esriSystem;
using ESRI.ArcGIS.Carto;
using ESRI.ArcGIS.Geodatabase;

namespace HookActions
{
    [Guid("0E620D8D-7B63-49ed-A3BF-55530A95B34F")]
    [ClassInterface(ClassInterfaceType.None)]
    [ProgId("HookActions.hookActionLabel")]
    public sealed class hookActionsLabel : BaseCommand
    {
        #region COM Registration Function(s)
        [ComRegisterFunction()]
        [ComVisible(false)]
        static void RegisterFunction(Type registerType)
        {
            // Required for ArcGIS Component Category Registrar support
            ArcGISCategoryRegistration(registerType);

            //
            // TODO: Add any COM registration code here
            //
        }

        [ComUnregisterFunction()]
        [ComVisible(false)]
        static void UnregisterFunction(Type registerType)
        {
            // Required for ArcGIS Component Category Registrar support
            ArcGISCategoryUnregistration(registerType);

            //
            // TODO: Add any COM unregistration code here
            //
        }

        #region ArcGIS Component Category Registrar generated code
        /// <summary>
        /// Required method for ArcGIS Component Category registration -
        /// Do not modify the contents of this method with the code editor.
        /// </summary>
        private static void ArcGISCategoryRegistration(Type registerType)
        {
            string regKey = string.Format("HKEY_CLASSES_ROOT\\CLSID\\{{{0}}}", registerType.GUID);
            GMxCommands.Register(regKey);
            MxCommands.Register(regKey);
            ControlsCommands.Register(regKey);
        }
        /// <summary>
        /// Required method for ArcGIS Component Category unregistration -
        /// Do not modify the contents of this method with the code editor.
        /// </summary>
        private static void ArcGISCategoryUnregistration(Type registerType)
        {
            string regKey = string.Format("HKEY_CLASSES_ROOT\\CLSID\\{{{0}}}", registerType.GUID);
            GMxCommands.Unregister(regKey);
            MxCommands.Unregister(regKey);
            ControlsCommands.Unregister(regKey);
        }

        #endregion
        #endregion

        private IHookHelper m_hookHelper = null;
        private IGlobeHookHelper m_globeHookHelper = null;

        public hookActionsLabel()
        {
            base.m_category = "HookActions";
            base.m_caption = "Create labels";
            base.m_message = "Create labels";
            base.m_toolTip = "Create labels";
            base.m_name = "HookActions_Label";
        }

        public override void OnCreate(object hook)
        {
            // Test the hook that calls this command and disable if nothing valid
            try
            {
                m_hookHelper = new HookHelperClass();
                m_hookHelper.Hook = hook;
                if (m_hookHelper.ActiveView == null)
                {
                    m_hookHelper = null;
                }
            }
            catch
            {
                m_hookHelper = null;
            }
            if (m_hookHelper == null)
            {
                //Can be globe
                try
                {
                    m_globeHookHelper = new GlobeHookHelperClass();
                    m_globeHookHelper.Hook = hook;
                    if (m_globeHookHelper.ActiveViewer == null)
                    {
                        //Nothing valid!
                        m_globeHookHelper = null;
                    }
                }
                catch
                {
                    m_globeHookHelper = null;
                }
            }

            if (m_globeHookHelper == null && m_hookHelper == null)
                base.m_enabled = false;
            else
                base.m_enabled = true;
        }

        public override bool Enabled
        {
            get
            {
                IHookActions hookActions = null;
                IBasicMap basicMap = null;

                //Get basic map and set hook actions
                if (m_hookHelper != null)
                {
                    basicMap = m_hookHelper.FocusMap as IBasicMap;
                    hookActions = m_hookHelper as IHookActions;
                }
                else if (m_globeHookHelper != null)
                {
                    basicMap = m_globeHookHelper.Globe as IBasicMap;
                    hookActions = m_globeHookHelper as IHookActions;
                }

                //Disable if no features selected
                IEnumFeature enumFeature = basicMap.FeatureSelection as IEnumFeature;
                IFeature feature = enumFeature.Next();
                if (feature == null) return false;

                //Enable if action supported on first selected feature
                if (hookActions.get_ActionSupported(feature.Shape, esriHookActions.esriHookActionsLabel))
                    return true;
                else
                    return false;
            }
        }

        public override void OnClick()
        {
            IHookActions hookActions = null;
            IBasicMap basicMap = null;

            //Get basic map and set hook actions
            if (m_hookHelper != null)
            {
                basicMap = m_hookHelper.FocusMap as IBasicMap;
                hookActions = m_hookHelper as IHookActions;
            }

            else if (m_globeHookHelper != null)
            {
                basicMap = m_globeHookHelper.Globe as IBasicMap;
                hookActions = m_globeHookHelper as IHookActions;
            }

            //Get feature selection 
            ISelection selection = basicMap.FeatureSelection;
            //Get enumerator
            IEnumFeature enumFeature = selection as IEnumFeature;
            enumFeature.Reset();
            //Set first feature
            IFeature feature;
            feature = enumFeature.Next();

            //Loop though the features
            IArray array = new ESRI.ArcGIS.esriSystem.Array();
            IStringArray sArray = new StrArray();
            while (feature != null)
            {
                //Add feature to array
                array.Add(feature.Shape);
                //Add the value of the first field to the string array
                sArray.Add(feature.get_Value(0).ToString());
                //Set next feature
                feature = enumFeature.Next();
            }

            //If the action is supported perform the action
            if (hookActions.get_ActionSupportedOnMultiple(array, esriHookActions.esriHookActionsLabel))
                hookActions.DoActionWithNameOnMultiple(array, sArray, esriHookActions.esriHookActionsLabel);
        }
    }
}