CODEWITHSUNDEEP
iosobjective-cuitableviewcore-data
virat
virat

Reputation: 117

Deleting data from table view crashes the app

Here the when i click on the delete button the application crashes giving error : attempt to insert nil object from objects[0]' Here is my code.

@implementation ViewDetailViewController

- (NSManagedObjectContext *)managedObjectContext
{
    NSManagedObjectContext *context = nil;
    id delegate = [[UIApplication sharedApplication] delegate];
    if ([delegate performSelector:@selector(managedObjectContext)]) {
        context = [delegate managedObjectContext];
    }
    return context;
}

- (void)viewDidLoad {
    [super viewDidLoad];


    // Fetch the devices from persistent data store
    NSManagedObjectContext *managedObjectContext = [self managedObjectContext];
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"Personal"];
    self.devices = [[managedObjectContext executeFetchRequest:fetchRequest error:nil] mutableCopy];

    self.searchResult = [NSMutableArray arrayWithArray:self.devices];

    [self.tableView reloadData];


    // Do any additional setup after loading the view, typically from a nib.
}


- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];

    // Fetch the devices from persistent data store
    NSManagedObjectContext *managedObjectContext = [self managedObjectContext];
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] initWithEntityName:@"Personal"];
    self.devices = [[managedObjectContext executeFetchRequest:fetchRequest error:nil] mutableCopy];

    self.searchResult = [NSMutableArray arrayWithArray:self.devices];

    [self.tableView reloadData];


    // Do any additional setup after loading the view.
}

Here are my table view delegate methods. 

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    // Return the number of sections.
    return 1;
}

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

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];

    // Configure the cell...
    NSManagedObject *device = [self.searchResult objectAtIndex:indexPath.row];

    {
        [cell.textLabel setText:[NSString stringWithFormat:@"%@", [device valueForKey:@"name"]]];
        [cell.detailTextLabel setText:[device valueForKey:@"attribute"]];
    }
    return cell;
}

Code for deleting data.

- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
{
    // Return NO if you do not want the specified item to be editable.
    return YES;
}


-(void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSManagedObjectContext *context = [self managedObjectContext];

    if (editingStyle == UITableViewCellEditingStyleDelete) {
        // Delete object from database
        [context deleteObject:[self.devices objectAtIndex:indexPath.row]];

        NSError *error = nil;
        if (![context save:&error]) {
            NSLog(@"Can't Delete! %@ %@", error, [error localizedDescription]);
            return;
        }
        static NSString *CellIdentifier = @"Cell";
        UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier forIndexPath:indexPath];
        NSIndexPath *cellIndexPath = [self.tableView indexPathForCell:cell];

        //Remove device from table view
        [self.devices removeObjectAtIndex:indexPath.row];
        [tableView deleteRowsAtIndexPaths:@[cellIndexPath] withRowAnimation:UITableViewRowAnimationFade];
    }
}

Upvotes: 0

Views: 102

Answers (3)

Lane
Lane

Reputation: 119

Try removing this line : [tableView deleteRowsAtIndexPaths:@[cellIndexPath] withRowAnimation:UITableViewRowAnimationFade]; It seems that u should not delete cells in commitEditingStyle.That delegate automatically does it.

Upvotes: 0

Keyur Hirani
Keyur Hirani

Reputation: 1607

Please this code may be use full

[self.searchResult removeObjectAtIndex:indexPath.row];
[tableview reload];

Upvotes: 0

iSashok
iSashok

Reputation: 2446

In your datasource methods you use self.searchResult

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

but in commitEditingStyle: you delete data from [self.devices removeObjectAtIndex:indexPath.row];

You need change this one

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

or change 

[self.searchResult removeObjectAtIndex:indexPath.row];

And one more thing you no need get cellIndexPath this params passed to method yet

-(void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
  NSManagedObjectContext *context = [self managedObjectContext];

 if (editingStyle == UITableViewCellEditingStyleDelete) {
            // Delete object from database
            [context deleteObject:[self.devices objectAtIndex:indexPath.row]];

            NSError *error = nil;
            if (![context save:&error]) {
                NSLog(@"Can't Delete! %@ %@", error, [error localizedDescription]);
                return;
            }

        //Remove device from table view
        [self.devices removeObjectAtIndex:indexPath.row];
        //[self.tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
        [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];

    }
}

Upvotes: 1

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