UITableView not reloading data after model data changes (cellForRowAtIndexPath not fired)

Question

For the app I'm currently working on, one of my main ViewControllers contains two UITableViews whose contents vary based on what's stored in my model (Core Data backed by SQL). Both tableviews set their delegate and datasource properties to the shared VC they're both subviews of, and I provide the necessary methods in the VC to respond to tableview-specific events.

I'm finding that when I add new data to my database that should cause the TableViews to show new rows, and I return to the VC and call reloadData on both TableViews in the VC's viewWillAppear method, I see that numberOfRowsInSection returns the correct number of rows based on the new entries in CoreData, but cellForRowAtIndexPath is not called the correct number of times, almost like it's not responding to the change in the model data. For example, if I had 3 rows to show then the app started, and I added another entry in CoreData, then called reloadData, numberOfRowsInSection returns 4 correctly, but cellForRowAtIndexPath is only called 3 times still.

Besides the fact that I probably be using something more suitable like NSFetchedResultsController to link my TableViews to CoreData, is there any reason why cellForRowAtIndexPath is not being called the correct number of times, as dictated by the correct number of rows returned by numberOfRowsInSection?

I would put in some of my code, but it's really standard boilerplate TableView stuff and I feel like there's something else that I'm missing.

Answer 1

Just to make sure you understand correctly, the cellForRowAtIndexPath: is called with the number of cell that can be in the screen. If you have 4 cells, but because the height of the cell, only 3 cells can be available to users, then the cellForRowAtIndexPath: is called 3 times

Answer 2

If the user can only see only 3 cells, not more, then the cell loading callbacks may only be called 3 times, even if there are 100's of rows in your table.