I have a very general table view.

when it is refreshed, it will go to fetch list of objects from Parse. Analyze these data in a dispatch\_async queue, then refresh table view. Most time, it has no problem, but some time reloadData() crash

[![enter image description here](https://i.stack.imgur.com/SyYUn.png)](https://i.stack.imgur.com/SyYUn.png) 

Is it crashes because the tableView is reloading data when I call it? (when the tableview is init, reloadData may be called automatically) How to avoid this error? ( there is no error message in console )

**EDIT:**
I tries to put `?`, but does not work

[![enter image description here](https://i.stack.imgur.com/NmuGj.png)](https://i.stack.imgur.com/NmuGj.png)