需要实现下面的两个方法

-(void)viewDidLayoutSubviews
{
  if ([self.tableview respondsToSelector:@selector(setSeparatorInset:)]) {
    [self.tableview setSeparatorInset:UIEdgeInsetsMake(0,0,0,0)];
  }

  if ([self.tableview respondsToSelector:@selector(setLayoutMargins:)]) {
    [self.tableview      setLayoutMargins:UIEdgeInsetsMake(0,0,0,0)];
  }
}
-(void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
{
  if ([cell respondsToSelector:@selector(setSeparatorInset:)]) {
    [cell setSeparatorInset:UIEdgeInsetsZero];
  }

  if ([cell respondsToSelector:@selector(setLayoutMargins:)]) {
    [cell setLayoutMargins:UIEdgeInsetsZero];
   }
}