CustomAction.cs

using System;
using Microsoft.Deployment.WindowsInstaller;

namespace ClosePromptCA
{
    public class CustomActions
    {
        [CustomAction]
        public static ActionResult ClosePrompt(Session session)
        {
            session.Log("Begin PromptToCloseApplications");
            try
            {
                var productName = session["ProductName"];
                var processes = session["PromptToCloseProcesses"].Split(',');
                var displayNames = session["PromptToCloseDisplayNames"].Split(',');

                if (processes.Length != displayNames.Length)
                {
                    session.Log(@"Please check that 'PromptToCloseProcesses' and 'PromptToCloseDisplayNames' exist and have same number of items.");
                    return ActionResult.Failure;
                }

                for (var i = 0; i < processes.Length; i++)
                {
                    session.Log("Prompting process {0} with name {1} to close.", processes[i], displayNames[i]);
                    using (var prompt = new PromptCloseApplication(productName, processes[i], displayNames[i]))
                        if (!prompt.Prompt())
                            return ActionResult.Failure;
                }
            }
            catch(Exception ex)
            {
                session.Log("Missing properties or wrong values. Please check that 'PromptToCloseProcesses' and 'PromptToCloseDisplayNames' exist and have same number of items. \nException:" + ex.Message);
                return ActionResult.Failure;
            }

            session.Log("End PromptToCloseApplications");
            return ActionResult.Success;
        }
    }
}