Modify a content block with the Native API

using System;
using System.Linq;
using Telerik.Sitefinity.GenericContent.Model;
using Telerik.Sitefinity.Modules.GenericContent;

namespace SitefinityWebApp
{
   public class ModifyContentBlockNativeAPI
   {
       public void ModifyContentItemNative(Guid masterContentItemId, string newContent)
       {
           ContentManager manager = ContentManager.GetManager();

           // Get the master version.
           ContentItem master = manager.GetContent().Where(cI => cI.Id == masterContentItemId).FirstOrDefault();

           if (master != null)
           {
               // Check out the master to get a temp version.
               ContentItem temp = manager.Lifecycle.CheckOut(master) as ContentItem;

               // Make the modifications to the temp version.
               temp.Content = newContent;

               // Check in the temp and get the updated master version. 
               // After the check in the temp version is deleted.
               master = manager.Lifecycle.CheckIn(temp) as ContentItem;

               // Publish the master.
               manager.Lifecycle.Publish(master);

               manager.SaveChanges();
           }
       }
   }
}