I ask this because I find it's strange that `heightForRowAtIndexPath` firstly work with the last cell in my tableView. 

Here's what I got, I've 13 sections, each section has only one cell. So when I called `reloadData` and log the `indexPath.section` in `heightForRowAtIndexPath`, the last section's indexPath got printed. Then it started from section 0, then 1, 2, 3, till 11 in order.

This is tested on both device & simulator and both iOS 7 & iOS 8.

Is this the fixed order or only for the case that I test?