Programming with Content Types in SharePoint 2010

// Programming with Content Types.
using System;
using System.Runtime.InteropServices;
using System.Security.Permissions;
using Microsoft.SharePoint;
using Microsoft.SharePoint.Security;
using System.Linq;
namespace SPHOL302_Ex2.Features.Feature1
{  
    [Guid("8c019752-8354-430b-ba1c-bed7daac7c48")]
    public class Feature1EventReceiver : SPFeatureReceiver
    {
        // Uncomment the method below to handle the event raised after a feature has been activated.
        public override void FeatureActivated(SPFeatureReceiverProperties properties)
        {
            using (SPWeb spWeb = properties.Feature.Parent as SPWeb)
            {
                SPContentType newAnnouncement = spWeb.ContentTypes.Cast<SPContentType>().FirstOrDefault(c => c.Name == "New Announcements");
                if (newAnnouncement != null)
                {
                    newAnnouncement.Delete();
                }
                SPField newField = spWeb.Fields.Cast<SPField>().FirstOrDefault(f => f.StaticName == "Team Project");
                if (newField != null)
                {
                    newField.Delete();
                }
                SPContentType myContentType = new SPContentType(spWeb.ContentTypes["Announcement"], spWeb.ContentTypes, "New Announcements");
                myContentType.Group = "Custom Content Types";
                spWeb.Fields.Add("Team Project", SPFieldType.Text, true);
                SPFieldLink projFeldLink = new SPFieldLink(spWeb.Fields["Team Project"]);
                myContentType.FieldLinks.Add(projFeldLink);
                SPFieldLink companyFieldLink = new SPFieldLink(spWeb.Fields["Company"]);
                myContentType.FieldLinks.Add(companyFieldLink);
                spWeb.ContentTypes.Add(myContentType);
                myContentType.Update();
            }
        }
        // Uncomment the method below to handle the event raised before a feature is deactivated.
        public override void FeatureDeactivating(SPFeatureReceiverProperties properties)
        {
            using (SPWeb spWeb = properties.Feature.Parent as SPWeb)
            {
                SPContentType myContentType = spWeb.ContentTypes["New Announcements"];
                spWeb.ContentTypes.Delete(myContentType.Id);
                spWeb.Fields["Team Project"].Delete();
            }
        }
        // Uncomment the method below to handle the event raised after a feature has been installed.
        //public override void FeatureInstalled(SPFeatureReceiverProperties properties)
        //{
        //}
        // Uncomment the method below to handle the event raised before a feature is uninstalled.
        //public override void FeatureUninstalling(SPFeatureReceiverProperties properties)
        //{
        //}
        // Uncomment the method below to handle the event raised when a feature is upgrading.
        //public override void FeatureUpgrading(SPFeatureReceiverProperties properties, string upgradeActionName, System.Collections.Generic.IDictionary<string, string> parameters)
        //{
        //}
    }
}
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