Assertion failure when i use the Add Function

Question

In a table, I have 3 indexes which calls each a function. In each function, there is an add button that adds data into CoreData. First 2 works, but when i press the 3rd index and press Add , this error appears.

2011-07-19 16:57:11.079 CoreDataMelaka[2704:207] * **Assertion failure in -[UITableView _endCellAnimationsWithContext:], /SourceCache/UIKit_Sim/UIKit-1447.6.4/UITableView.m:976**
2011-07-19 16:57:11.080 CoreDataMelaka[2704:207] **Serious application error.  Exception was caught during Core Data change processing.  This is usually a bug within an observer of NSManagedObjectContextObjectsDidChangeNotification.  Invalid update: invalid number of rows in section 0.  The number of rows contained in an existing section after the update (0) must be equal to the number of rows contained in that section before the update (0), plus or minus the number of rows inserted or deleted from that section (1 inserted, 0 deleted). with userInfo (null)****

here's the code for 3rd class that i call

@implementation MainFoodsInfoController

@synthesize mainfoods;
@synthesize mainfoodsarray;
@synthesize fetchedResultsController;
@synthesize tableView;
@synthesize foodsbutton;
@synthesize editfoodsbutton;
@synthesize addfoodsbutton;


-(IBAction) foodslist:(id) sender 
{
    [self dismissModalViewControllerAnimated:YES];
}


-(IBAction) addmainfoods:(id)sender 
{
    NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
    AddMainFoodsController *addmainfoodsController=[[AddMainFoodsController alloc] initWithNibName:@"AddMainFoodsController" bundle:nil];
    addmainfoodsController.delegate=self;   
    addmainfoodsController.mainfoods =  [NSEntityDescription insertNewObjectForEntityForName:@"MainFoods" inManagedObjectContext:context];
    UINavigationController *navigatController=[[UINavigationController alloc] initWithRootViewController:addmainfoodsController];
    [self   presentModalViewController:navigatController animated:YES]; 
    [addmainfoodsController release];
    [navigatController release];
}


-(IBAction) editmainfoods:(id)sender 
{
    if([editfoodsbutton.title isEqualToString:@"Edit"]) 
    {
        editfoodsbutton.title=@"Done"; 
        [self.tableView setEditing:YES animated:YES];
    } 
    else 
    {
        editfoodsbutton.title=@"Edit"; 
        [self.tableView setEditing:NO animated:YES];
    }
}

-(void) addmainfoodsController:(AddMainFoodsController *)controller selectedsave:(BOOL) save 
{
    NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
    if(!save) {
        [context deleteObject:controller.mainfoods];
    } 
    NSError *error; if(![context save:&error])
    {
        NSLog(@"Unresolved error %@ %@", error, [error userInfo]); exit(-1);
    } 
    [self dismissModalViewControllerAnimated:YES];
}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView 
{
    NSInteger count = [[self.fetchedResultsController sections] count];
    if (count == 0) 
    {
        count = 1;
    }
    return count;   
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section 
{
    NSInteger numofRows = 0;
    if ([[self.fetchedResultsController sections] count] > 0) 
    {
        id <NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController sections] objectAtIndex:section];
        numofRows = [sectionInfo numberOfObjects];
    }
    return numofRows;
}

// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:CellIdentifier];
    if (cell == nil) 
    { 
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease]; 
        cell.accessoryType=UITableViewCellAccessoryDisclosureIndicator;
    }    

    // Configure the cell.
    NSManagedObject *managedObject = [fetchedResultsController objectAtIndexPath:indexPath];
    cell.textLabel.text = [[managedObject valueForKey:@"foodsname"] description];
    UIImage *pimage=[managedObject valueForKey:@"foodstableimage"]; 
    CGSize size=pimage.size; 
    CGFloat ratio = 0; if (size.width > size.height) 
    {
        ratio = 44.0 / size.width;
    } 
    else 
    {
        ratio = 44.0 / size.height;
    }
    CGRect rect = CGRectMake(0.0, 0.0, ratio * size.width, ratio * size. height);
    UIGraphicsBeginImageContext(rect.size); 
    [pimage drawInRect:rect]; 
    cell.imageView.image=UIGraphicsGetImageFromCurrentImageContext(); 
    UIGraphicsEndImageContext(); 
    return cell;
}

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath 
{
    EditMainFoodsController *editmainfoodsController = [[EditMainFoodsController alloc] initWithNibName:@"EditMainFoodsController" bundle:nil];
    MainFoods *selectedmainfoods = (MainFoods *) [fetchedResultsController objectAtIndexPath:indexPath];
    editmainfoodsController.mainfoods= selectedmainfoods;
    UINavigationController *naviggController=[[UINavigationController alloc] initWithRootViewController:editmainfoodsController];
    [self presentModalViewController:naviggController animated:YES];
}

// Override to support editing the table view.
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *) indexPath 
{
    if (editingStyle == UITableViewCellEditingStyleDelete) 
    { // Delete the managed object for the given index path
        NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
        [context deleteObject:[[self fetchedResultsController] objectAtIndexPath:indexPath]];
        NSError *error; if (![context save:&error]) 
        {
            // Handle the error...
        }
    }   
}

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];
    NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    [fetchRequest setEntity:[NSEntityDescription entityForName:@"MainFoods" inManagedObjectContext:context]];
    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"foodsname" ascending:YES];
    NSArray *sortDescriptors =[[NSArray alloc] initWithObjects:sortDescriptor,nil]; 
    [fetchRequest setSortDescriptors:sortDescriptors];
    self.tableView.rowHeight=44.0;
    NSError *error=nil;
    mainfoodsarray=(NSMutableArray *)[context executeFetchRequest:fetchRequest error:&error];   
    [sortDescriptor release];
    [sortDescriptors release];
    [fetchRequest release];
    [self.tableView reloadData];     
}

- (void)viewDidLoad {
    [super viewDidLoad];
    self.title=@"Foods Info";
    NSError *error;
    if (![[self fetchedResultsController] performFetch:&error]) {
        // Handle the error...
    }   


}

- (NSFetchedResultsController *)fetchedResultsController {
    if (fetchedResultsController != nil) {
        return fetchedResultsController;
    }

    CoreDataMelakaAppDelegate *appDelegate = (CoreDataMelakaAppDelegate *)[[UIApplication sharedApplication] delegate];
    NSManagedObjectContext *context = [appDelegate managedObjectContext];
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    [fetchRequest setEntity:[NSEntityDescription entityForName:@"MainFoods" inManagedObjectContext:context]];
    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"foodsname" ascending:YES];
    NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
    [fetchRequest setSortDescriptors:sortDescriptors];
    NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:context sectionNameKeyPath:nil cacheName:@"Root"];
    aFetchedResultsController.delegate = self;
    self.fetchedResultsController = aFetchedResultsController;
    [aFetchedResultsController release];
    return fetchedResultsController;
}    

- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath {
    switch(type) {
        case NSFetchedResultsChangeInsert:
            [self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
            break;
        case NSFetchedResultsChangeDelete:
            [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
            break;
    }
}

- (void)didReceiveMemoryWarning {
    // Releases the view if it doesn't have a superview.
    [super didReceiveMemoryWarning];

    // Release any cached data, images, etc. that aren't in use.
}

- (void)viewDidUnload {
    [super viewDidUnload];
    // Release any retained subviews of the main view.
    // e.g. self.myOutlet = nil;
}


- (void)dealloc {
    [foodsbutton release];
    [editfoodsbutton release];
    [addfoodsbutton release];
    [tableView release];
    [super dealloc];
}

@end

and here's the add class that causes the crash. When i press add, i want this class to be called but this causes a crash, the other 2 classes had no issue only this has the issue

@implementation AddMainFoodsController

@synthesize savebutton; 
@synthesize cancelbutton; 
@synthesize delegate; 
@synthesize foodsnewname; 
@synthesize foodsnewinfo; 
@synthesize foodsnewemailid;
@synthesize foodsnewcontactno;
@synthesize foodsimage1;
@synthesize foodsimage2;
@synthesize foodsimage3;
@synthesize foodstableimage;
@synthesize mainfoods;
@synthesize tempImage;

NSInteger countaddfoods = 0;

-(IBAction) cancel:(id) sender 
{
    [delegate addmainfoodsController: self selectedsave:NO];
}

-(IBAction) save:(id)sender
{ 
    mainfoods.foodsname = foodsnewname.text; 
    mainfoods.foodsemailid = foodsnewemailid.text; 
    mainfoods.foodscontactno = foodsnewcontactno.text;
    mainfoods.foodsinfo = foodsnewinfo.text;
    [delegate addmainfoodsController: self selectedsave:YES ];
}

-(IBAction) selectimagebutton1:(id)sender
{
    UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init] ;
    imagePicker.delegate = self;
    [self presentModalViewController:imagePicker animated:YES];
    [imagePicker release];
}

-(IBAction) selectimagebutton2:(id)sender
{
    UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init] ;
    imagePicker.delegate = self;
    [self presentModalViewController:imagePicker animated:YES];
    [imagePicker release];
}

-(IBAction) selectimagebutton3:(id)sender
{
    UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init] ;
    imagePicker.delegate = self;
    [self presentModalViewController:imagePicker animated:YES];
    [imagePicker release];
}

-(IBAction) selecttableimagebutton:(id)sender
{
    UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init] ;
    imagePicker.delegate = self;
    [self presentModalViewController:imagePicker animated:YES];
    [imagePicker release];
}


- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)selectedImage editingInfo:(NSDictionary *)editingInfo
{
    tempImage = selectedImage;
    countaddfoods = countaddfoods + 1;

    [self setImage];
    [self dismissModalViewControllerAnimated:YES]; 
}

-(void) setImage
{
    if (countaddfoods == 1)
    {
        foodsimage1.image = tempImage;
        mainfoods.foodsimage1 = tempImage;
    }
    else if (countaddfoods == 2)
    {
        foodsimage2.image = tempImage;
        mainfoods.foodsimage2 = tempImage;
    }
    else if (countaddfoods == 3)
    {
        foodsimage3.image = tempImage;
        mainfoods.foodsimage3 = tempImage;
    }
    else 
    {
        foodstableimage.image = tempImage;
        mainfoods.foodstableimage = tempImage;
    }
}

- (void)imagePickerControllerDidCancel:(UIImagePickerController *)picker
{
    [self dismissModalViewControllerAnimated:YES];
}

- (void)viewDidLoad 
{
    [super viewDidLoad]; self.title=@"New Foods"; 
    self.navigationItem.rightBarButtonItem = savebutton; 
    self.navigationItem.leftBarButtonItem = cancelbutton;
}

- (void)dealloc 
{ 
    [savebutton release]; 
    [cancelbutton release]; 
    [foodsnewname release]; 
    [foodsnewemailid release]; 
    [foodsnewcontactno release]; 
    [foodsnewinfo release];
    [foodsimage1 release];
    [foodsimage2 release];
    [foodsimage3 release];
    [foodstableimage release];
    [mainfoods release]; 
    [tempImage release];
    [super dealloc];
} 

@end

Answer 1

The error message tells you the problem:

Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update (0) must be equal to the number of rows contained in that section before the update (0), plus or minus the number of rows inserted or deleted from that section (1 inserted, 0 deleted). with userInfo (null)**

In your table section (0), you started with zero rows i.e. an empty section. Then you added 1 row so the section(0) row count should be 1 but numberOfRowsInSection: is returning zero.

There are three probable causes for this problem:

1. You didn't freeze the tableview with beginUpdate in controllerWillChangeContent: such that the tableview tries to redraw itself before the update completes.
2. Your numberOfRowsInSection returns the wrong row count for the section.
3. You are inserting one managed object multiple times or you have a validate on insert/update that fails.

Can't tell you the actual problem without the code.

Answer 2

return [[[self.fetchedResultsController sections] objectAtIndex:section] numberOfObjects];

At least it worked for me

Answer 3

I faced the same error. I was using the delegate of NSFetchedResultsControllerDelegate. I comment rest of the delegate except the below one.

func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {  
 self.tableView.reloadData()
 if self.fetchedResultsController.fetchedObjects?.count == 0 {
    } else {
  }
}

If you want to use all delegate then you need properly manage rows and section. This error occur when you don't manage rows and section properly.