UITableView reloadData does not seem to cause cellForRowAtIndexPath: to be called

Question

I am currently writing an app, using storyboards, that contains two UITableViews within the same window.

When running the application, the first UITableView will populate with a number of "Registration Numbers".

When the user taps on a cell, then the second UITableView is supposed to populate with detail about the selected cell.

When tapping a number in the first table I have a method that drives the:

[mySecondTableView reloadData]

Which it does. I am under the impression that when invoking the reloadData command, it should then call both:

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section

and

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath

The first fires, but the second won't. I have both the data source and delegate wired to self.

I am not sure what I am missing.

Are both methods meant to fire?

Solution 1

When things like this happen to me, it's usually because I'm calling -reloadData outside of the main thread.

Solution 2

After reloadData, try this:

NSIndexSet * sections = [NSIndexSet indexSetWithIndex:0];
[self.tableView reloadSections:sections withRowAnimation:UITableViewRowAnimationNone];

I found if the data change is subtle, the table view seems to optimize away the need to refresh.

Solution 3

Pointed answers doesn't solve my table view problem. It was still calling

-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section

however cell drawing method wasn't fired:

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath

My problem was that(because of my mistake of course) table view height was 0. So as table displays only cells that are visible, it never tries to display a cell. When I changed height value drawing cell method started to fire again.

Botom line double check your table frame and ensure you have non-zero width and height values!

Solution 4

Make sure you call performSelectorOnMainThread with waitUntilDone:NO, otherwise you may still have the same issue

Solution 5

I just incurred this same issue. I used a performSelectorOnMainThread to call a method which then calls the reloadData. This was necessary since I was trying to update outside the main thread as suggested by hatfinch.

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Comments

[Bart Jacobs]

This is something so easily overlooked especially when working with completion handlers invoked from background threads. Excellent tip.

[olivaresF]

For some reason, this actually fixed it for me. That's wrong!

[Grey Code]

@OlivaresF - Thanks, this worked for me, moves inside cellForRowAtIndexPath. but not refreshing in TableView.

[srinivas]

indexSetwithindex methods are no longer available in swift, and i am facing this same reloaddata problem

[jbcaveman]

Banged my head on this for hours. Finally got it to work after reading this. Thanks. Be careful of completion blocks like Bart says. Make sure you call [tableView performSelectorOnMainThread:@selector(reloadData) withObject:nil waitUntilDone:NO]

[Max Friedman]

the only thing that worked for me after days of headaches. WHY XCODE WHY