NSFetchedResultsController W/ Custom Table Cell Incompatible Pointer - ios

Question

I've been trying to get a grip on CoreData. After several attempts to find a good tutorial on it I made a lot of progress with a tutorial on youtube. However when I got to the NSFetchedResultsController I'm getting a warning on my custom table cell ITDContactCell *cell = [tableView cellForRowAtIndexPath:indexPath] stating that it's an incompatible pointer initializing with UITableViewCell (the tutorial does not use custom cells).
Even worse, when I attempt to add an item I get this nice ugly error.
2013-12-04 19:15:48.407 Ping[490:60b] * Assertion failure in
-[UITableView _endCellAnimationsWithContext:], /SourceCache/UIKit/UIKit-2903.23/UITableView.m:1138 2013-12-04
19:15:48.409 Ping[490:60b] CoreData: error: Serious application error.
An exception was caught from the delegate of
NSFetchedResultsController during a call to
-controllerDidChangeContent:. attempt to insert row 0 into section 0, but there are only 0 rows in section 0 after the update with userInfo
(null)
I've spent hours trying to figure out what I'm doing wrong but I can't wrap my head around it. So if anyone can take a gander at my code and give me suggestions on how I can fix it I'd greatly appreciate it. Thank you.
Controller:
-(void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath {
UITableView *tableView = self.ContactsListTableView;
switch (type) {
case NSFetchedResultsChangeInsert:
[tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeDelete:
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeUpdate: {
Contact *changeContact = [self.fetchedResultsController objectAtIndexPath:indexPath];
ITDContactCell *cell = [tableView cellForRowAtIndexPath:indexPath];
cell.name.text = [NSString stringWithFormat:#"%# %#", changeContact.contactFirstName, changeContact.contactLastName];
}
break;
case NSFetchedResultsChangeMove:
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
[tableView insertRowsAtIndexPaths:[NSArray arrayWithObjects:newIndexPath, nil] withRowAnimation:UITableViewRowAnimationFade];
break;
}
}
EDIT: My implementation of number of rows and sections.
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
return [[self.fetchedResultsController sections]count];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
id<NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController sections]objectAtIndex:section];
return [sectionInfo numberOfObjects];
}
fetchedResultsController is defined in the interface simply as #property (strong, nonatomic) NSFetchedResultsController *fetchedResultsController

Answer 1

The warning is referring to the fact that the method
[tableView cellForRowAtIndexPath:indexPath];
returns a UITableViewCell, which is not literally your ITDContactCell. Placing a cast before the method should remove the warning.
ITDContactCell *cell = (ITDContactCell*) [tableView cellForRowAtIndexPath:indexPath];
The other error is probably because of some lack of relationship between your fetchedResultsController and your tableView. Showing your tableView delegate and source methods would help. I assume you have already implemented something similar:
-(void)viewWillAppear:(BOOL)animated {
[super viewWillAppear:animated];
NSError *error = nil;
if(![self.fetchedResultsController performFetch:&error]) {
// NSLog(#"Error! %#", error);
}
}
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return _fetchedResultsController.sections.count;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
id <NSFetchedResultsSectionInfo> secInfo = [[self.fetchedResultsController sections] objectAtIndex:section];
return [secInfo numberOfObjects];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
ITDContactCell *cell = (ITDContactCell *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
// assign cell content
return cell;
}
-(NSString *) tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section {
return [[[self.fetchedResultsController sections] objectAtIndex:section] name];
}
-(NSFetchedResultsController *) fetchedResultsController {
if(_fetchedResultsController != nil) {
return _fetchedResultsController;
}
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"EntityName"
inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
_fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest
managedObjectContext:self.managedObjectContext
sectionNameKeyPath:nil
cacheName:nil];
_fetchedResultsController.delegate = self;
return _fetchedResultsController;
}
-(void)controllerWillChangeContent:(NSFetchedResultsController *)controller {
[self.tableView beginUpdates];
}
-(void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
[self.tableView endUpdates];
}
-(void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath {
UITableView *tableView = self.ContactsListTableView;
switch (type) {
case NSFetchedResultsChangeInsert:
[tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeDelete:
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeUpdate: {
Contact *changeContact = [self.fetchedResultsController objectAtIndexPath:indexPath];
ITDContactCell *cell = [tableView cellForRowAtIndexPath:indexPath];
cell.name.text = [NSString stringWithFormat:#"%# %#", changeContact.contactFirstName, changeContact.contactLastName];
}
break;
case NSFetchedResultsChangeMove:
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
[tableView insertRowsAtIndexPaths:[NSArray arrayWithObjects:newIndexPath, nil] withRowAnimation:UITableViewRowAnimationFade];
break;
}
}
EDIT 1:
As a note, you should not be using the reloadData method in your tableview, since the table is reloaded (via the fetched results controller) after saving changes to your NSManagedObjectContext.
EDIT 2:
Is you NSManagedObjectContext nil?