Question

I have read several articles about UITableView, including the official doc and some on SO. But my situation seems to be different.
I want to update the Table each time the view loaded. And I must fetch the data using HTTP request.
What I got now is:

1. When enter the table view, I should use a non-synchronous HTTP request to update the data. Because I don’t want the main thread to wait. One place to do that, is in the tableView:cellForRowAtIndexPath: method. So I return 0 for no data exist at the beginning.
2. When I get the HTTP respond, I update rows on main thread using beginUpdates endUpdates insertRowsAtIndexPaths:withRowAnimation:
3. And I must update the “Data Source” at the same time, but how to do that?
   Or should I make a daemon thread and update my data every once in a while? So that the data will be ready when TableView is loaded.

Answer 1

You would do it like this:

• Have a boolean or some variable where you can reliably detect whether you have all the data.
• In viewWillAppear, reset everything. Start loading your data.
• If you don’t have the data yet, you only display one section with one cell (a placeholder cell that reads “Loading…” and shows a spinner, for instance).
• Once the data is completely loaded, you set the bool or whatever.
• Call [self.tableView reloadData];

In all of your UITableViewDataSource methods you would need to check whether you’ve got the data already or not. If not, you return the placeholder data.