问TableViewCell的textLabel和detailTextLabel无法正常工作

EN

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"bookCell";
    UITableViewCell *cell;
    cell= [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];

    cell=[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];

  // Book *bookDetail=[booksArrayDataSource objectAtIndex:indexPath.row];


    cell.accessoryType=UITableViewCellAccessoryDetailDisclosureButton;

    cell.textLabel.text= [self titleForRow:indexPath];
    NSLog(@"title for row= %@", cell.textLabel.text);

    cell.detailTextLabel.text= [self subtitleForRow:indexPath];
    NSLog(@"subtitle for row= %@",cell.detailTextLabel.text);

    return cell;
}