Managing Tasks Permissions Programmatically within SharePoint using event reciever or using special permissions property

I was writing a workflow using SharePoint designer wherein at certain steps tasks were getting created and assigned to different user. But the problem with that was that any user having appropriate rights on the tasks list was able to edit the task.

Below are the two methods using which we can have only the assigned to user having the rights on that task.

It can be done using Event Receiver or within the SharePoint workflow using special permissions property.

public override void ItemAdded(SPItemEventProperties properties)

        {

                // Name of the List

            if (properties.ListTitle == “Tasks”)

            {     

                // Get the SPSite Object

                SPSite objSite = new SPSite(“http://servername:portname”);       

                // Point to the top level web site within it

                SPWeb objWeb = objSite.OpenWeb();

                // get the task list item getting created

                SPListItem myListItem = properties.ListItem;       

                // get the id of the assigned to user

                // we want that only assigned to user should have full rights on that task

                string userAssignedTo=myListItem["Assigned To"].ToString();

                int index = userAssignedTo.IndexOf(‘;’);

                int id = Int32.Parse(userAssignedTo.Substring(0, index));

                // get the SPUser from the id

                SPUser user = objWeb.SiteUsers.GetByID(id);                       

                // break the role inheritance

                myListItem.BreakRoleInheritance(false);

                // webroledefinitions – Full Right, Design, Contribute and Read

                SPRoleDefinitionCollection webroledefinitions = objWeb.RoleDefinitions;

                SPRoleAssignment roleassignment = new SPRoleAssignment(user);              

                roleassignment.RoleDefinitionBindings.Add(webroledefinitions["Full Control"]);

                myListItem.RoleAssignments.Add(roleassignment);

                // give full control right to the assigned to user

                roleassignment.Update();                           

               }

            }

Or within workflow as

    // handler for create task activity

        private void createTask1_MethodInvoking(object sender, EventArgs e)

        {

            //Specify properties for the task

            createTask1.TaskProperties.AssignedTo = @”domainusername”;

            createTask1.TaskProperties.Title = @”Please complete the task”;

            createTask1.TaskProperties.Description = “This is sample SharePoint Task”;

            createTask1.TaskProperties.DueDate = DateTime.Now.AddDays(7);

            createTask1.TaskProperties.EmailBody = “This is the sample<b><i> email body </b></i>”;

            createTask1.TaskProperties.SendEmailNotification = true;

            // Define a HybridDictionary object

            HybridDictionary permsCollection = new HybridDictionary();

            // Give Administrator rights to the user to whom the task has been assigned

            permsCollection.Add(createTask1.TaskProperties.AssignedTo, SPRoleType.Administrator);

            // SpecialPermissions -the SpecialPermissions property  in your code will strip out all existing permissions inherited from

            // the parent list(Workflow Task List) and only adds permissions for each pair you added to the hashtable

            createTask1.SpecialPermissions = permsCollection;   

        }