2 different types of custom UITableViewCells in UITableView

You should create a different cell identifier for the two styles of cell:

- (UITableViewCell *) tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{

int feedIndex = [indexPath indexAtPosition:[indexPath length] - 1];
Feed *item = [[[[self selectedButton] category] feedsList] objectAtIndex:feedIndex + 1];

static NSString *CellIdentifier1 = @"Cell1";
static NSString *CellIdentifier2 = @"Cell2";

if(feedIndex == 0) {

   MainArticleTableViewCell *cell = (MainArticleTableViewCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier1];

   if (cell == nil) {
       cell = [[[MainArticleTableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:CellIdentifier1] autorelease];
       [[[cell subviews] objectAtIndex:0] setTag:111];
   }

   cell.feed = item;

   return cell;
}
else {
   NewsTableViewCell *cell = (NewsTableViewCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier2];

   if (cell == nil) {
       cell = [[[NewsTableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:CellIdentifier2 orientation:currentOrientation] autorelease];
       [[[cell subviews] objectAtIndex:0] setTag:111];
   }

   cell.feed = item;

   return cell;
}

return nil;
}