Question

I have a grouped UITableView in my UIViewController class and I’m finding that at times, the dequeued cell is not nil as expected.

The table has 3 sections to start with and and as soon as the ‘viewDidLoad’ is invoked, a server call is initiated to find out if there are more sections. Before the view is even rendered, the server’s response arrives and we’re told that we have 4 sections. To deal with this change, I do:

[self.tableview beginUpdates]

// Do the updating of the array that holds table data

[self.tableview endUpdates]
[self.tableview reloadData];

Next I get the call to ‘numberOfSectionsInTableView’, for which I return 4, followed by ‘numberOfRowsInSection’ and I’m returning the expected correct row count. Note this is the first time I’m getting either of these calls since the table reload happened so quickly and before the view was even rendered.

At this point, only the data from the 1st 3 sections are visible and scroll to view the last section. When you scroll to see the last section, one of the cells I’m expecting to be in the call to ‘tableView:cellForRowAtIndexPath’ is not nil as expected. The cell type is actually what was used for another section (I have one type of UITableViewCell for the 1st two sections and another for the last two sections that I’m creating and handing back in cellForRowAtIndexPath when cell is nil).

So how does UITableView figure out which cell to dequeue and how do I figure out why this cell for this particular section/row is not nil when it really should be?

Answer 1

What are you using for your cell identifier? That’s what a UITableView will use when determining what to dequeue. If you have different types of cells, you’ll need different reuse identifiers.