Can't programmatically delete row from UITableView

Question

I'm trying to implement a custom deletion process for my app, as my costumer doesn'y want the red circle provided by table view edition mode. I have added a deletion button for every row, with row number in its tag property. Once user clicks deletion button, it fires following method:

-(IBAction)deleteRow:(id)sender{

    UIButton *tempButton = (UIButton*)sender;

   [self updateTotals];

    NSIndexPath *indexPath = [NSIndexPath indexPathForRow:tempButton.tag inSection:0];

    [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]  withRowAnimation:UITableViewRowAnimationFade];

    [tableView reloadData];

    [sharedCompra removeItem:tempButton.tag];

    tempButton=nil;


}

And I allways get this error:

Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid update: invalid number of rows in section 0.  The number of rows contained in an existing section after the update (3) must be equal to the number of rows contained in that section before the update (3), plus or minus the number of rows inserted or deleted from that section (0 inserted, 1 deleted) and plus or minus the number of rows moved into or out of that section (0 moved in, 0 moved out).'

So I don't know if I'm missing something in this piece of code.

Many thanks.

user529758 · Accepted Answer · 2012-11-10 17:09:47Z

12

You're trying to delete a row whereas your data source still reflects the original state (i. e. that before the deletion). You have to update the data source first, it's only then that you can issue a deletion from the table viev. You also don't need to set the button to nil, nor do you need to call - reloadData on the table view:

- (void)deleteRow:(id)sender
{
    UIButton *tempButton = sender;
    [self updateTotals];

    NSIndexPath *indexPath = [NSIndexPath indexPathForRow:tempButton.tag inSection:0];
    [sharedCompra removeItem:tempButton.tag];

    [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]  withRowAnimation:UITableViewRowAnimationFade];
}

(One thing you should do, however, is paying attention to how you format your code.)

answered Nov 10, 2012 at 17:09

user529758

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Comments

Tomasz Zabłocki · Accepted Answer · 2012-11-10 17:16:30Z

1

Call [sharedCompra removeItem:tempButton.tag]; before [tableView deleteRowsAtIndexPaths... and [tableView reloadData]

The problem is that when you call deleteRowsAtIndexPath: it is calling numberOfRowsInSection which returns the same count from your model.

Also reloadData call is not needed here.

edited Nov 10, 2012 at 17:16

answered Nov 10, 2012 at 17:07

Tomasz Zabłocki

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Comments

Maximilian Litteral · Accepted Answer · 2012-11-10 19:42:46Z

0

When deleting and adding rows, you need to call beginUpdates, here how it should look.

[tableView beginUpdates];
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]  withRowAnimation:UITableViewRowAnimationFade];
[tableView endUpdates];

and you don't need to call reloadData, or it will cancel the animation of the deleteRows, and insertRows methods. But you do need to reset the data, so if you're using an NSMutableArray, you need to remove the object first, so item at index 0, then you can delete row 0 in table. the number of rows needs to match the number of objects in that array when it ends deleting or it will also crash.

edited Nov 10, 2012 at 19:42

user529758

answered Nov 10, 2012 at 17:12

Maximilian Litteral

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2 Comments

user529758 Over a year ago

Um, no. You do not need to call - beginUpdates and - endUpdates. The problem is not that.

rmaddy Over a year ago

You use beginUpdates and endUpdates when you are inserting/deleting/reloading multiple rows and you need the index paths to remain consistent throughout. But as @H2CO3 stated, that is completely unrelated to this question.

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