perform new fetch in core data iphone - iphone

I am doing core data fetches using the standard code provided by Apple, it has the following statement in the beginning of the fetch method.
- (NSFetchedResultsController *)fetchedResultsController {
if (fetchedResultsController_ != nil) {
return fetchedResultsController_;
}
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:self.entityName inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
// Set the batch size to a suitable number.
[fetchRequest setFetchBatchSize:20];
// Edit the sort key as appropriate.
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:self.sortFieldName ascending:YES];
NSMutableArray *sortDescriptors = [[NSMutableArray alloc] initWithObjects:sortDescriptor, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
if(predicate != nil)
[fetchRequest setPredicate:predicate];
// Edit the section name key path and cache name if appropriate.
// nil for section name key path means "no sections".
NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:sectionKeyName cacheName:nil];
aFetchedResultsController.delegate = self;
self.fetchedResultsController = aFetchedResultsController;
[aFetchedResultsController release];
aFetchedResultsController = nil;
[fetchRequest release];
fetchRequest = nil;
[sortDescriptor release];
[sortDescriptors release];
NSError *error = nil;
if (![fetchedResultsController_ performFetch:&error]) {
}
return fetchedResultsController_;
}
The first time, fetchedResultsController gets the required info. But I am setting a predicate on this result after that. So, I would like the fetch to consider my predicate the next time. If it goes in the above code, it will come out immediately because the old value is not nil.
To overcome this, after setting the predicate, I do
fetchedResultsController_ = nil;
This works ok,but is giving leaks at the fetchedResultsController as soon as the fetchRequest is allocated.
Is there a better way to re-execute the fetch or to avoid the leak?

Just add a release.
if(fetchedResultsController_){
[fetchedResultsController_ release];
}
fetchedResultsController_ = nil;

Related

Core data doesn't fetch objects

Hello here is my NSFetchedResultsController implementation:
-(NSFetchedResultsController *)fetchedResultsController
{
if (_fetchedResultsController != nil) {
return _fetchedResultsController;
}
NSLog(#"context - %#",self.context);
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription
entityForName:#"Categories" inManagedObjectContext:self.context];
[fetchRequest setEntity:entity];
NSSortDescriptor *sort = [[NSSortDescriptor alloc]
initWithKey:#"name" ascending:YES];
[fetchRequest setSortDescriptors:#[sort]];
[fetchRequest setFetchBatchSize:20];
NSFetchedResultsController *theFetchedResultsController =
[[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest
managedObjectContext:self.context sectionNameKeyPath:nil
cacheName:#"root"];
_fetchedResultsController = theFetchedResultsController;
_fetchedResultsController.delegate = self;
// [[self context] fetchObjectsForEntityName:#"Categories" withPredicate:
// nil] ;
return _fetchedResultsController;
}
fetchedResultsController.fetchedObjects is always nil.
Here is how I'm adding objects:
-(void)addCategoryWithName:(NSString *)name
{
NSLog(#"context - %#",self.context);
Categories *category = (Categories *)[NSEntityDescription insertNewObjectForEntityForName:#"Categories" inManagedObjectContext:self.context];
category.name = name;
NSLog(#"category name - %#",category.name);
category.displayOrder = [NSNumber numberWithFloat:1.0f];
// site.displayOrder = displayOrder;
NSError __block *error;
if (![self.context save:&error]){
NSLog(#"Error saving - %#", [error localizedDescription]);
}
}
There is no error, no nothing. If I see my .sqlite file in the Documents directory it's modified, but I can't get any objects fetched. Really weird, I'm using fundamentally the same codes for my other app and it works just fine.
Any ideas?
You have to call performFetch on the fetched results controller once. Otherwise it will not fetch anything and also not track changes. For example add
NSError *error;
if (![_fetchedResultsController performFetch:&error]) {
// error handling
}
at the end of the fetchedResultsController getter method.
Remark: It seems that specifying a cacheName without sectionNameKeyPath can cause problems, see UITableView with NSFetchedResultsController Does Not Load the Second Time. Since the cache is used to cache section information, it is not needed anyway if you don't have sections.
Update: The preceding remark is no longer valid, it turned out that the problems in the linked question had a different cause.

NSFetchResultsController delegate not getting called

I have the following code:
- (NSFetchedResultsController *)fetchedResultsController {
// Set up the fetched results controller if needed.
if (fetchedResultsController == nil) {
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
// Edit the entity name as appropriate.
NSEntityDescription *entity = [NSEntityDescription entityForName:#"DiskStory" inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
fetchRequest.predicate = [NSPredicate predicateWithFormat:#"isRemoved == %#", [NSNumber numberWithBool:NO]];
// Edit the sort key as appropriate.
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"created" ascending:NO];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
// Set limit
[fetchRequest setFetchBatchSize:25];
// Set batch size
[fetchRequest setFetchLimit:50];
NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:kSavedStoryCache];
aFetchedResultsController.delegate = self;
fetchedResultsController = aFetchedResultsController;
}
return fetchedResultsController;
}
in my viewDidLoad I have:
NSError *error = nil;
if (![[self fetchedResultsController] performFetch:&error]) {
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
}
I was wondering why my :
- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
}
delegate, isn't called? I put a break point inside it. Any idea?
I had this problem before, it's not called when you call performFetch for the first time but only when data in fetchedResultsController is actually changed. For instance when you delete object from context that is in this fetch results, delegate will be called.
I think you have used self. at wrong places. Please see the code below; i have added comments to the changes
- (NSFetchedResultsController *)fetchedResultsController {
// Set up the fetched results controller if needed.
if (fetchedResultsController == nil) {
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
// Edit the entity name as appropriate.
NSEntityDescription *entity = [NSEntityDescription entityForName:#"DiskStory" inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
fetchRequest.predicate = [NSPredicate predicateWithFormat:#"isRemoved == %#", [NSNumber numberWithBool:NO]];
// Edit the sort key as appropriate.
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"created" ascending:NO];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
// Set limit
[fetchRequest setFetchBatchSize:25];
// Set batch size
[fetchRequest setFetchLimit:50];
NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:kSavedStoryCache];
aFetchedResultsController.delegate = self;
fetchedResultsController = aFetchedResultsController; // -> Shouldn't be self.fetchedResultsController
}
return fetchedResultsController; // -> Shouldn't be self.fetchedResultsController
}
Also, if you have synthesize your fetchedResultsController as follows:
fetchedResultsController = _fetchedResultsController
Then in - (NSFetchedResultsController *)fetchedResultsController method you should refer to it as _fetchedResultsController

IPad Core Data Leak?

Im using XCode 3.2.3 and have created an app using the SplitView template with Core Data.
When i run the default app on the device (3.2) in debug mode with instruments running
i am seeing a leak.
When the default app has no items added to the table view within the split view there is no leak.
But after adding items and running the app a leak is reported.
Responsible Frames are ....
NSPushAutoreleasePool
+[NSThread currentThread]
WTF:initializeMainThreadPlatform()
WTF:initializeMainThreadPlatform()
WTF:initializeMainThreadPlatform()
I beleive the issue happens when fetchedResultsController is called
- (NSFetchedResultsController *)fetchedResultsController {
if (fetchedResultsController != nil) {
return fetchedResultsController;
}
/*
Set up the fetched results controller.
*/
// Create the fetch request for the entity.
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
// Edit the entity name as appropriate.
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Event" inManagedObjectContext:managedObjectContext];
[fetchRequest setEntity:entity];
// Set the batch size to a suitable number.
[fetchRequest setFetchBatchSize:20];
// Edit the sort key as appropriate.
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"timeStamp" ascending:NO];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
// Edit the section name key path and cache name if appropriate.
// nil for section name key path means "no sections".
NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:managedObjectContext sectionNameKeyPath:nil cacheName:#"Root"];
aFetchedResultsController.delegate = self;
self.fetchedResultsController = aFetchedResultsController;
[aFetchedResultsController release];
[fetchRequest release];
[sortDescriptor release];
[sortDescriptors release];
return fetchedResultsController;
}
Any advice or pointers appreciated.

Empty FetchedResultsController in Core Data

I'm using core data and I have an entity defined called LogRecord. Elsewhere this is populated with objects using:
LogRecord *rec = [NSEntityDescription insertNewObjectForEntityForName:#"LogRecord"
inManagedObjectContext:managedObjectContext];
[rec timestampNow];
rec.moodType = [NSNumber numberWithUnsignedInteger:i];
rec.moodValue = value;
NSError *error = nil;
if (![rec.managedObjectContext save:&error]) {
[DataUtil displayFatalError:error message:#"Failed to save log entry"];
errors++;
}
I've checked and the underlying sqlite database has records in it after using this code.
However, when I try to query for the data using this:
- (NSFetchedResultsController *)fetchedResultsController {
if (fetchedResultsController == nil) {
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"LogRecord"
inManagedObjectContext:managedObjectContext];
[fetchRequest setEntity:entity];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"timestamp" ascending:NO];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
// nil for section name key path means "no sections".
NSFetchedResultsController *aFetchedResultsController =
[[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest
managedObjectContext:managedObjectContext
sectionNameKeyPath:nil
cacheName:nil];
aFetchedResultsController.delegate = self;
self.fetchedResultsController = aFetchedResultsController;
[aFetchedResultsController release];
[fetchRequest release];
[sortDescriptor release];
[sortDescriptors release];
}
return fetchedResultsController;
}
It comes up empty as evidenced by [[self.fetchedResultsController sections] count] returning zero.
Any idea how I might debug this? It was working before I tried to break this code out into a different UIViewController....
Never mind.... Somehow the call to [[self fetchedResultsController] performFetch:&error] in viewDidLoad got deleted.

Core Data , NSFetchResultsController leaking

I am not sure if the leak is in my implementation or is it from apple's side....
Instruments indicate me that I have a leak in this line :
if (![[self fetchedResultsController]
performFetch:&error])
I am adding annotations by reading the fetchController to the Map.... like this :
-(void)fillMapWithAnnotations{
NSError *error = nil;
if (![[self fetchedResultsController] performFetch:&error]) {
NSLog(#"Unresolved error %#, %#", error, [error userInfo]);
abort();
}
for(int a=0; a<[[[fetchedResultsController sections]objectAtIndex:0] numberOfObjects]; a++){
LookAround *look=(LookAround *)[fetchedResultsController objectAtIndexPath:[NSIndexPath indexPathForRow:a inSection:0]];
if(look){
AddAnnotation *newAnnotation=[[AddAnnotation alloc]initWithLookAround:look];
if(newAnnotation){
[self.mapView addAnnotation:newAnnotation];
[newAnnotation release];
newAnnotation=nil;
}
}
}
}
and I initialize my FetchController like this:
- (NSFetchedResultsController *)fetchedResultsController{
// Set up the fetched results controller if needed.
if (fetchedResultsController == nil) {
// Create the fetch request for the entity.
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
// Edit the entity name as appropriate.
NSEntityDescription *entity = [NSEntityDescription entityForName:#"LookAround" inManagedObjectContext:managedObjectContext];
[fetchRequest setEntity:entity];
// Edit the sort key as appropriate.
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"name" ascending:YES];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
// Edit the section name key path and cache name if appropriate.
// nil for section name key path means "no sections".
NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:managedObjectContext sectionNameKeyPath:nil cacheName:#"Root"];
aFetchedResultsController.delegate = self;
self.fetchedResultsController = aFetchedResultsController;
[aFetchedResultsController release];
[fetchRequest release];
[sortDescriptor release];
[sortDescriptors release];
}
return fetchedResultsController;
}
I get a leak as soon as i Navigate Back, the ViewController gets Deallocated in which I release my fetch controller object.
The objects that leak are numerous (and of the same type I guess) around the number of records in my sqlite DB
Thanks in advance for your help....
As I noted above, the leak is probably in your AddAnnotation class.