uiTableView crashes the second time in deleting a cell - iphone

Question

I'n new in iPhone, I'm trying to delete a cell from my UITableView, the first time it deletes well, but the second time it gives me the following 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).'
here is my code of table:
- (void)tableView:(UITableView *)tableView commitEditingStyle: (UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
Book_own *temp= (Book_own *)[self.books objectAtIndex:indexPath.row];
if (editingStyle == UITableViewCellEditingStyleDelete) {
// Delete the row from the data source
[books removeObjectAtIndex:indexPath.row];
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
isDeleted = #"true";
deletedBook_id = temp.bo_id;
[self viewDidLoad];
}
else if (editingStyle == UITableViewCellEditingStyleInsert) {
// Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
}
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
// Return the number of sections.
return 2;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
// Return the number of rows in the section.
NSDictionary *dictionary = [listOfItems objectAtIndex:section];
NSArray *array = [dictionary objectForKey:#"myBooks"];
return [array count];
}
in ViewDidLoad I wrote the following code:
NSDictionary *mbooks = [NSDictionary dictionaryWithObject:books forKey:#"myBooks"];
NSDictionary *mgroups = [NSDictionary dictionaryWithObject:filteredParts forKey:#"myBooks"];
listOfItems = [[NSMutableArray alloc] init];
[listOfItems addObject:mbooks];
[listOfItems addObject:mgroups];
Can anyone tell me how to solve this issue??
Thanks in advance.

Answer 1

What is happening is that you are either not deleting the item or you are deleting only one item when you allow multible deleting. You can adjust by checking if it is really deleted as below or reload data if not:
// Override to support editing the table view.
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if (editingStyle == UITableViewCellEditingStyleDelete) {
// Delete the row from the data source
BOOL success = [self removeFile:indexPath];
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
if (!success) [tableView reloadData];
}
}
This method then removes the datasource item (it is from my own project so the names should be adjusted:
-(BOOL) removeFile:(NSIndexPath *)indexPath{
// Removes from the datasource and the filesystem
NSURL *fileURL = [self.dataSource objectAtIndex:indexPath.row];
NSError *error;
BOOL success = [[NSFileManager defaultManager] removeItemAtURL:fileURL error:&error];
if (success) {
[self.dataSource removeObjectAtIndex:indexPath.row];
} else {
UIAlertView *alert = [[UIAlertView alloc]initWithTitle:#"Error" message:[error localizedDescription] delegate:self cancelButtonTitle:#"Ok" otherButtonTitles: nil];
[alert show];
[alert release];
[self.dataSource removeObjectAtIndex:indexPath.row];
}
return success;
}

Answer 2

If I'm reading your code correctly your data source is listOfItems. You should remove the row from your tables data source. A general rule is that when you remove or add items to a UITableView you must update the databsource.
[listOfItemsremoveObjectAtIndex:indexPath.row];

Answer 3

First, do not call [self viewDidLoad]; This method should not be called manually.
I think you are not calling the update method to your table view. This might fix your problems:
[tableView beginUpdates];
[books removeObjectAtIndex:indexPath.row];
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
[tableView endUpdates];
edit: you also need to look at your code more closely. You are deleting a record from your datasource array directly from the row of the indexPath, which could be problematic considering the fact that your tableView has two sections.

Answer 4

The error says that there should be 1 fewer row after the deletion. It fails because the datasource code is not consistent in how it reports about the model.
Look at how you answer numberOfRowsInSection. Correctly, I think, first picking out the array that the section index represents, then answering that array's count.
The same logic must apply on the delete. The array you delete from needs to be the array indicated by the indexPath.section. Consider this:
- (void)tableView:(UITableView *)tableView commitEditingStyle: (UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {
// the array you manipulate here must be the same array you use to count
// number of rows, and the same you use to render rowAtIndexPath
NSDictionary *dictionary = [listOfItems objectAtIndex:indexPath.section];
NSArray *array = [dictionary objectForKey:#"myBooks"];
// in order to be edited, it must be mutable
// you can do that on the fly here, or set it up as mutable
// let's make it temporarily mutable here:
NSMutableArray *mutableCopy = [array mutableCopy];
if (editingStyle == UITableViewCellEditingStyleDelete) {
[mutableCopy removeObjectAtIndex:indexPath.row];
// if it's setup mutable, you won't need to replace the immutable copy in the dictionary.
// but we just made a copy, so we have to replace the original
[listOfItems replaceObjectAtIndex:indexPath.section withObject:[NSArray arrayWithArray:mutableCopy]];
// and so on