I can create new managed objects inside my app, in a separate view I have a table view which shows all the objects I have.
When I create a new managed object (in a totally separate view), I am sending out a notification which is trying to get my table view to reload with the new data which includes the new object i just made.
I'm not editing the table view.
There is only one managed context.
I can't grasp what I am doing wrong. If I close the app and relaunch my new object is in the table view. I am trying to call reloadData when I get the notification a new object has been made, and I've also tried performing the fetch again, but all I end up with is an empty table view.
In terms of code, my ListViewController:
@interface MyNotesViewController : UIViewController
{
NSManagedObjectContext * __managedObjectContext;
UITableView * _notesTableView;
MyNotesTableViewDelegate_DataSource * _tableDelegate_DataSource;
}
My viewDidLoad looks like this:
- (void)viewDidLoad
{
[super viewDidLoad];
_tableDelegate_DataSource = [[MyNotesTableViewDelegate_DataSource alloc] init];
_tableDelegate_DataSource.managedObjectContext = __managedObjectContext;
[_notesTableView setDataSource:_tableDelegate_DataSource];
NSError * _coreDataError;
BOOL success = [[_tableDelegate_DataSource fetchedResultsController] performFetch:&_coreDataError];
if(success){
[_notesTableView reloadData];
}
}
In my delegate/datasource object I have:
@interface MyCommutesTableViewDelegate_DataSource : NSObject
<UITableViewDataSource, NSFetchedResultsControllerDelegate>
{
NSManagedObjectContext * __managedObjectContext;
NSFetchedResultsController * __fetchedResultsController;
}
@property (nonatomic, retain) NSManagedObjectContext *managedObjectContext;
@end
Implementation excerpt:
-(NSFetchedResultsController*)fetchedResultsController{
if(!__fetchedResultsController){
NSFetchRequest * request = [[NSFetchRequest alloc] init];
[request setEntity:[NSEntityDescription entityForName:@"Note" inManagedObjectContext:__managedObjectContext]];
[request setFetchBatchSize:10];
NSSortDescriptor * sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"noteDate" ascending:NO];
[request setSortDescriptors:[NSArray arrayWithObject:sortDescriptor]];
[sortDescriptor release];
__fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request managedObjectContext:__managedObjectContext sectionNameKeyPath:nil cacheName:nil];
__fetchedResultsController.delegate = self;
[request release];
}
return __fetchedResultsController;
}
I have the stander UITableView data source methods here:
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView {
return 1;
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{
id <NSFetchedResultsSectionInfo> sectionInfo =
[[__fetchedResultsController sections] objectAtIndex:section];
return [sectionInfo numberOfObjects];
}
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = @"NotesTableViewCell";
NotesTableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
NSArray * topLevelObjects = [[NSBundle mainBundle] loadNibNamed:@"NotesTableViewCell" owner:nil options:nil];
for(id currentObject in topLevelObjects){
if([currentObject isKindOfClass:[UITableViewCell class]]){
cell = (NotesTableViewCell*) currentObject;
break;
}
}
}
// Configure the cell.
Note * _note = [__fetchedResultsController objectAtIndexPath:indexPath];
[...]
return cell;
}
UPDATE
I reverted to simply requesting all objects because I had to quick fix my problem, and then I realised, after I save my context, my fetch request I had previously used on the app launch, now returns no data, there's no error but it just returns nothing.
So I guess there's no issue with how I'm implementing NSFetchResultsController. But how could the request start not returning results after I save a new object ?
Note I still get all of my objects if I relaunch, including the newly added one.
standard request:
-(NSArray*)getNotes{
NSFetchRequest * request = [[NSFetchRequest alloc] init];
NSEntityDescription * entity = [NSEntityDescription entityForName:@"Note" inManagedObjectContext:[self managedObjectContext]];
[request setEntity:entity];
NSSortDescriptor * sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"noteDate" ascending:NO];
[request setSortDescriptors:[NSArray arrayWithObject:sortDescriptor]];
[sortDescriptor release];
NSError * coreDataError;
NSArray * fetchedObjects = [[self managedObjectContext] executeFetchRequest:request error:&coreDataError];
[request release];
if(fetchedObjects != nil){
return fetchedObjects;
} else {
NSLog(@"ERR: %@", coreDataError);
return nil;
}
}
I am waiting for a notification telling me a new object has been added to Core Data, and then I am calling the above method and then calling reloadData on my tableview...
