multiple selection in grouped tableview
===

I am working with grouped tableview with multiple sections. 
and I have to implement the functionality of multiple selection on didselectrow at indexpath
method. my code is as follows.

    - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)path {
    UITableViewCell *cell = [tableView cellForRowAtIndexPath:path];
     if (cell.accessoryType == UITableViewCellAccessoryCheckmark) {
    cell.accessoryType = UITableViewCellAccessoryNone;
    } else {
    cell.accessoryType = UITableViewCellAccessoryCheckmark;
    }
    } 

which allows me to select multiple cells
but when I scroll my tableview at that time my selection disappears.

what should be the issue plz provide me solution if you have.

thanx in advance.

   