分组UITableView统计cell索引

创建一个索引计数给分组织UITableView的所有cell。我已经存储到正确位置了，但是提取的时候提取不出来。

索引代码：

indexPath.section = 0   
  indexPath.row = 0     cellIndex = 0
  indexPath.row = 1     cellIndex = 1
  indexPath.row = 2     cellIndex = 2
  indexPath.row = 3     cellIndex = 3
  indexPath.row = 4     cellIndex = 4

indexPath.section = 1
  indexPath.row = 0     cellIndex = 5
  indexPath.row = 1     cellIndex = 6
  indexPath.row = 2     cellIndex = 7
  indexPath.row = 3     cellIndex = 8

方程式：

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSInteger cellIndex = numberOfSections * indexPath.section + indexPath.row;
}

在外面定义一个累加器不行？

NSInteger cellIndex=0;

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    ++cellIndex;
    NSLog(@"current cell index:%d",cellIndex);
}