UITableView "cellForRowAtIndexPath" not working

Question

I'm trying to use "reloadData" method on a uitableView, it seems like it works (both dataSource method are being called) and when I debug "cellForRowAtIndexPath" the cell that it returns is the correct cell) but I can't see the cell (numberOfRowsInSection is changing and adding blank space for each new cell - So it's not seems to be a threads problem). For example, if I have in the tableView 5 "names" (my data array called "namesArray") and I add 2 there will be 5 names and 2 nil cells presented on the tableView. The problem seems to be with cellForRowAtIndexPath.

cellForRowAtIndex:

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
//Creating "cellIdentifier"(NSString) with "Cell" as the value
NSString *cellIdentifier=@"Cell";

[tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:cellIdentifier];

//Creating a default cell using "cellIdentifier"(NSString)
UITableViewCell *cell=[tableView dequeueReusableCellWithIdentifier:cellIdentifier forIndexPath:indexPath];
if (cell==nil) {
    cell=[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
}

cell.textLabel.text=[namesArray objectAtIndex:indexPath.row];

//Returning cell
return cell;
}

numberOfRowsInSection:

-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return self.namesArray.count;
}

-(void)addNameToNamesArray:(NSString*)name
 {
     [self.namesArray addObject:name];
     NSLog(@"namesArray lastObject: %@",[self.namesArray lastObject]);
    //NSLog print: The correct name (the one that was added)

    [self.tableView reloadData];
 }

screenshot for "5 names and 2 nil cells": Do you have any idea what can it be?

What do you mean by nil cells? Could you post a screenshot perhaps? — Jason, Dec 23 '15 at 14:00
Is the array initialized..? How about yuo paste the entire class here — Ankit Srivastava, Dec 23 '15 at 14:01
use namesArray as datasource of your tableView,and also initialise your names array — Arslan Asim, Dec 23 '15 at 14:03
@AnkitSrivastava It's really long class... but namesArray is initialized on "viewDidLoad" — Yhper, Dec 23 '15 at 14:11
@Yhper Is namesArray NSMutableArray? And How many times cellForRowAtIndexPath returning cell put counter int it ans NSLog it.. — Krishna Kumar, Dec 23 '15 at 14:24
How could you tell that `it's adding blank space for each new cell`? I don't see any wrong about these codes. Could you `NSLog(@"%@", [NSThread isMainThread]);` in `addNameToNamesArray`? — user3480295, Dec 23 '15 at 14:29
I think it will be not possible to help you to find problem if you will not post here all code of `.m` file. If `delegate` is set and your `cellIdentifier` is correct - the the problem is that: you are adding new objects but then you rewrite it / or you are adding `empty names` - and that because you get empty cells. 1. Check new name before adding. 2. Check new array in `numberOfRowsInSection` — Nazir, Dec 23 '15 at 15:15
@Nazir Can you give me your email and I'll send you my project, maybe you'll be able to help? — Yhper, Dec 23 '15 at 15:30
@ArslanAsim Can you give me your email and I'll send you my project, maybe you'll be able to help? — Yhper, Dec 23 '15 at 15:31
Which is the place where you call addNameToNamesArray: method? if it is on a button press ...perhaps the button press is getting more than one time with empty data that gets added into your array or something like that. — Anand, Dec 23 '15 at 17:23
@Yhper there is no way to public here email securely. Share link with project google/docs or dropbox — Nazir, Dec 24 '15 at 12:23

Jason · Answer 1 · 2015-12-23T14:15:00.697

0

This is likely because you have updated the data in your array, but the table view hasn't accessed that data yet, leading to the nil cells that you see. Since your cells load properly with the initial 5 element in your array, it's probable that you simply haven't refreshed the table view's data. Try using [tableView reloadData] after you have added the new elements to your array.

EDIT 1 What about changing your cellForRowAtIndexPath code to this:

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    //Creating "cellIdentifier"(NSString) with "Cell" as the value
     NSString *cellIdentifier=@"Cell";

    //Creating a default cell using "cellIdentifier"(NSString)
     UITableViewCell *cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];

     cell.textLabel.text = [self.namesArray objectAtIndex:indexPath.row];
     NSLog(@"name: %@", cell.textLabel.text);

    //Returning cell
     return cell;
}

Let us know the output of NSLog.

edited Dec 23 '15 at 14:15

answered Dec 23 '15 at 13:55

Jason

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That's what I do, updated the post with some code, please take a look – Yhper Dec 23 '15 at 13:56
3

Shouldn't the "numberOfRowsInSection return self.namesArray.count? – Jason Dec 23 '15 at 13:59
It is return self.namesArray.count – Yhper Dec 23 '15 at 14:08
No, it always was like that – Yhper Dec 23 '15 at 14:20
Could you verify that "addNameToNamesArray" is being run on the main thread? Where is it being called? – Jason Dec 23 '15 at 14:34
And did you try removing the cell dequeue code, and replacing it with your own initialised cells? – Jason Dec 23 '15 at 14:35
Copy and paste the code I've got above and see what happens. It looks like it could be something to do with you reusing the cells. Otherwise the only other explanation to why they are nil is that they somehow are being run on a background thread. – Jason Dec 23 '15 at 14:41
Also, check your UITableView in Storyboard and make sure that you've added at least one prototype cell - with the identifier as "Cell". Refer to this: http://stackoverflow.com/questions/13379547/dequeuereusablecellwithidentifier-always-returns-nil-not-using-storyboard – Jason Dec 23 '15 at 14:45

Sailendra · Answer 2 · 2015-12-23T14:12:39.903

change to

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
//Creating "cellIdentifier"(NSString) with "Cell" as the value
static NSString *cellIdentifier=@"Cell";

//[tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:cellIdentifier];

//Creating a default cell using "cellIdentifier"(NSString)
UITableViewCell *cell=[tableView dequeueReusableCellWithIdentifier:cellIdentifier];
if (cell==nil) {
    cell=[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
}

cell.textLabel.text=[namesArray objectAtIndex:indexPath.row];

//Returning cell
return cell;
}

-(NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    return self.namesArray.count;
}

set the outlet of tableview and then in addNameToNamesArray method after adding elements reload the tableview

Tried it, still the same problem – Yhper Dec 23 '15 at 14:16 — Yhper, Dec 23 '15 at 14:16

score 0 · Answer 3 · answered Dec 23 '15 at 14:02

0

You call

[tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:cellIdentifier];

inside cellForRowAtIndexPath!

Don't you think that's a bit late? And if it worked, you would be calling it a bit often?

And if dequeue... returns nil when a class is registered, something is badly wrong.

answered Dec 23 '15 at 14:02

gnasher729

51,477
5
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Tried to move it to "viewDidLoad", same problem – Yhper Dec 23 '15 at 14:08

score 0 · Answer 4 · edited Dec 23 '15 at 14:31

1.Make sure you have initialized self.namesArray in viewDidLoad

Try the following:

[tableView registerClass:[UITableViewCell class]forCellReuseIdentifier:cellIdentifier];

like below:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *cellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];
    if (!cell) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
    }

    cell.textLabel.text = [namesArray objectAtIndex:indexPath.row];

    return cell;
 }

dequeueReusableCellWithIdentifier is always returns nil for some reason — Yhper, Dec 23 '15 at 14:31

score 0 · Answer 5 · answered Dec 23 '15 at 14:40

0

Your code is perfectly alright. There can be some possibilities that its not working for you.

You are not initialising your datasource i.e NSMutableArray in your case.
It depends how you are calling addNameToNamesArray method.

If you can share your whole code for that class as how you are calling method and every delegates you are using.

answered Dec 23 '15 at 14:40

Krishna Kumar

1,652
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Can you give me your email and I'll send you my project, maybe you'll be able to help? – Yhper Dec 23 '15 at 15:31
@Yhper relentless.krishna@gmail.com – Krishna Kumar Dec 23 '15 at 22:03

UITableView "cellForRowAtIndexPath" not working

5 Answers5