TableView or FetchedResultController Error - getting a blank row - ios

Question

I have a simple app that create some object. Everything works fine but if i press the add button that open a detailViewController and there i will press cancel instead of saving it goes back to de mainTableView but it show a blank row, if i open the sql file there's no empty object so it should be an issue between the fetchedResultController and tableView loading it.
i know its not the best way to add an Object because in my add action i create an entity even if the user wont save. Yet it shouldnt show the blank row. Why is that happening? How to fix?
This is my code:
IngredietnViewController.m
#import "IngredientsTableViewController.h"
#interface IngredientsTableViewController ()
#end
#implementation IngredientsTableViewController
#synthesize managedObjectContext = _managedObjectContext;
#synthesize fetchedResultsController = _fetchedResultsController;
#synthesize ingredient = _ingredient;
- (void)viewDidLoad
{
[super viewDidLoad];
self.title = #"Ingredients";
UIBarButtonItem *addButton = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:#selector(addIngredient)];
self.navigationItem.rightBarButtonItem = addButton;
self.navigationItem.leftBarButtonItem = self.editButtonItem;
self.tableView.tableFooterView = [[UIView alloc] init];
}
#pragma mark - Table view data source
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return [[self.fetchedResultsController sections] count];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
id <NSFetchedResultsSectionInfo> sectionInfo = [self.fetchedResultsController sections][section];
NSLog(#"%lu", (unsigned long)[sectionInfo numberOfObjects]);
return [sectionInfo numberOfObjects];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
}
// Configure the cell...
[self configureCell:cell atIndexPath:indexPath];
return cell;
}
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if (editingStyle == UITableViewCellEditingStyleDelete) {
NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
[context deleteObject:[self.fetchedResultsController objectAtIndexPath:indexPath]];
NSError *error = nil;
if (![context save:&error]) {
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
}
}
#pragma mark - Action
-(void)addIngredient{
DetailIngredientViewController *detailIngredientVC =[[DetailIngredientViewController alloc]initWithNibName:#"DetailIngredientViewController" bundle:nil];
detailIngredientVC.delegate = self;
self.ingredient = [NSEntityDescription insertNewObjectForEntityForName:#"Ingredient" inManagedObjectContext:self.managedObjectContext];
detailIngredientVC.detailIngredient = self.ingredient;
[self.navigationController pushViewController:detailIngredientVC animated:YES];
}
#pragma mark - Table view delegate
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{}
#pragma mark - Fetched Result
- (NSFetchedResultsController *)fetchedResultsController
{
if (_fetchedResultsController != nil) {
return _fetchedResultsController;
}
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Ingredient" inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
[fetchRequest setFetchBatchSize:20];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"name" ascending:NO];
NSArray *sortDescriptors = #[sortDescriptor];
[fetchRequest setSortDescriptors:sortDescriptors];
NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:#"Master"];
aFetchedResultsController.delegate = self;
self.fetchedResultsController = aFetchedResultsController;
NSError *error = nil;
if (![self.fetchedResultsController performFetch:&error]) {
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
return _fetchedResultsController;
}
- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller
{
[self.tableView beginUpdates];
}
- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type
{
switch(type) {
case NSFetchedResultsChangeInsert:
[self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeDelete:
[self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
break;
}
}
- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject
atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type
newIndexPath:(NSIndexPath *)newIndexPath
{
UITableView *tableView = self.tableView;
switch(type) {
case NSFetchedResultsChangeInsert:
[tableView insertRowsAtIndexPaths:#[newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeDelete:
[tableView deleteRowsAtIndexPaths:#[indexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeUpdate:
[self configureCell:[tableView cellForRowAtIndexPath:indexPath] atIndexPath:indexPath];
break;
case NSFetchedResultsChangeMove:
[tableView deleteRowsAtIndexPaths:#[indexPath] withRowAnimation:UITableViewRowAnimationFade];
[tableView insertRowsAtIndexPaths:#[newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
}
}
- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller
{
[self.tableView endUpdates];
}
#pragma mark - configureCell:
- (void)configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath
{
Ingredient *object = [self.fetchedResultsController objectAtIndexPath:indexPath];
cell.textLabel.text = object.name ;
cell.detailTextLabel.text = object.rappresentation;
}
-(void)controller:(UIViewController *)controller didSaveIngredient:(Ingredient *)DetailIngredient{
NSLog(#"INGREDIENT SAVED");
NSError *error = nil;
if (![self.managedObjectContext save:&error]){
NSLog(#"Error %# %#", error, [error userInfo]);
}
[self.tableView reloadData];
}
#end
DeataiIngredientlViewController.m
#implementation DetailIngredientViewController
#synthesize tfNameIngredient, detailIngredient, tvDescription;
- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
if (self) {
// Custom initialization
}
return self;
}
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view from its nib.
UIBarButtonItem *saveButton = [[UIBarButtonItem alloc]initWithBarButtonSystemItem:UIBarButtonSystemItemSave target:self action:#selector(saveIngredient)];
self.navigationItem.rightBarButtonItem = saveButton;
}
-(void)saveIngredient{
if ([self verifyIngredient] == YES){
detailIngredient.name = tfNameIngredient.text;
detailIngredient.rappresentation = tvDescription.text;
[self.delegate controller:self didSaveIngredient:detailIngredient];
[self.navigationController popToRootViewControllerAnimated:YES];
}
else{
NSLog(#"SBALLATA");
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Error" message:#"The Name and description are empty" delegate:self cancelButtonTitle:#"Back" otherButtonTitles:nil, nil];
[alert show];
}
}
-(BOOL)verifyIngredient{
if ([tfNameIngredient.text length] < 4 || [tvDescription.text length] < 4 ){
return NO;
}
else{
return YES;
}
}
#end

Answer 1

Your blank row corresponds to Ingredient NSManagedObject you created in addIngredient.
Even though you didn't save: the NSManagedObjectContext it still exists and is picked up by your NSFetchedResultsController.
When the user cancels the add you need to delete it. Perhaps add a controller:(UIViewController *)controller didCancelAddIngredient: method to your delegate?
ALSO, in controller:(UIViewController *)controller didSaveIngredient: you don't need to reloadData on your UITableView, that's what all that NSFetchedResultsControllerDelegate code is there to do for you.