Custom cells with textfields and Core Data

Question

I have a tableview and i made a custom cell with two textfields...i want the text in the textfields to be saved in core data, so i created the core data class for that purpose and i know how to implement the core data methods.

I´m having trouble understanding how can i display the cell in the tableview, so that the user enters the text and then he get´s saved in core data. From my understanding these are the steps:

1 - the tableview loads and displays the custom cell by default with the textfields.

2 - the user enters the text, hits enter and he get´s saved in core data.

My problem is how can i perform number 1, i cannot load data in view did load because there is no data YET!, i have to display the cell first.

Can anyone help me with this issue, let me understand what am i missing here? this is my code so far:

- (void)viewDidLoad
{

AppDelegate *appDelegate =[[UIApplication sharedApplication] delegate];
self.managedObjectContext=[appDelegate managedObjectContext];


NSError *error;
if (![[self fetchedResultsController] performFetch:&error]) {
    /*
     Replace this implementation with code to handle the error appropriately.

     abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
     */
    NSLog(@"Unresolved error %@, %@", error, [error userInfo]);

}

[self fetchedResultsController];


[super viewDidLoad];
}

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{

return [[self.fetchedResultsController sections] count];
}

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [[[self.fetchedResultsController sections] objectAtIndex:section] numberOfObjects];
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath

{
static NSString *CellIdentifier = @"machines";

cellMeios *cellM = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

if (cellM == nil) {
    cellM = [[cellMeios alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}

return cellM;
}

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

// Create and configure a fetch request.
NSFetchRequest *fetchRequestMo = [[NSFetchRequest alloc] init];
NSEntityDescription *entityMo = [NSEntityDescription entityForName:@"Mo" inManagedObjectContext:self.managedObjectContext];
[fetchRequestMo setEntity:entityMo];

// Create the sort descriptors array.
NSSortDescriptor *cellTitle = [[NSSortDescriptor alloc] initWithKey:@"reference" ascending:YES];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:cellTitle, nil];
[fetchRequestMo setSortDescriptors:sortDescriptors];

// Create and initialize the fetch results controller.
_fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequestMo managedObjectContext:self.managedObjectContext sectionNameKeyPath:@"reference" cacheName:nil];
_fetchedResultsController.delegate = self;
self.fetchedResultsController = _fetchedResultsController;

return _fetchedResultsController;
}

There are the other methods but i think they are not relevant for my problem, the thing is...i need to display something to the user so that he can fill up!

I already have another tableview working with core data but in that case, the table is supose to be empty at first, then there´s a plus button on the top of the tableview and THEN he choses something and it get´s saved in core data displaying a cell with relevant information.

Thanks in advance Regards.

Answer 1

If you intend the table view to be editable, you should have a method like insertNewObject that would be triggered when the user hits the '+' (plus) button in the navigation bar. The implementation of this method creates a new managed object, inserts it in the context, and reloads the table. You could also trigger this method when the fetchedResultsController comes back empty.

Here's a version from one of my view controllers:

- (void)insertNewObject:(id)sender
{
    NSManagedObjectContext *context = [self.managedObject managedObjectContext];
    NSRelationshipDescription *relation = [[self.managedObject entity] relationshipsByName][self.relationship];
    NSEntityDescription *destinationEntity = [relation destinationEntity];
    NSManagedObject *newManagedObject = (NSManagedObject*)[NSEntityDescription insertNewObjectForEntityForName:[destinationEntity name] inManagedObjectContext:context];

    if ([relation isOrdered]) {
        [self.items insertObject:newManagedObject atIndex:[self.items count]];
    }
    else {
        NSMutableSet *set = [self.managedObject mutableSetValueForKey:self.relationship];
        [set addObject:newManagedObject];
        self.items = [NSMutableOrderedSet orderedSetWithSet:set];
    }

    // Save the context.
    NSError *error = nil;
    if (![context save:&error]) {
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        [[[UIAlertView alloc] initWithTitle:NSLocalizedString(@"Validation Error", @"Validation Error") message:[error localizedDescription] delegate:nil cancelButtonTitle:NSLocalizedString(@"OK", @"OK") otherButtonTitles: nil, nil] show];
    }
    [self.tableView reloadData];
}