Background-queue changes to parent NSManagedObjectContext in UIManagedDocument cause duplicate in NSFetchedresultsController on merge - core-data

Question

Ok guys. This one is driving me up the wall. I have
UIManagedDocument and its 2 MOContexts (regular and parent.)
A UITableViewController (subclassed to CoreDataTableViewController by Paul Hegarty) that runs off of an
NSFetchedResultsController
A background GCD Queue for syncing with the server that the parent cue accesses
I've tried this so many different ways and I run into problems each time.
When I add a new "animal" entity, it is no problem and immediately shows up on the table. But when I upload it to the server (on the upload queue) and changed its "status" (with the parent context) so that it should be in the uploaded section, it appears there but doesn't disappear from the un-uploaded section.
I END UP WITH TWINS I DIDN'T WANT! or it doesn't even make the correct one sometimes and just keeps the wrong one.
***BUT, the extra one will disappear when the app is shut down and reloaded. So it's just in memory somewhere. I can verify in the store that everything is correct. But the NSFetchedResultsController isn't firing the controllerDidChange... stuff.
Here is the superclass of my view controller
CoreDataTableViewController.m
#pragma mark - Fetching
- (void)performFetch
{
self.debug = 1;
if (self.fetchedResultsController) {
if (self.fetchedResultsController.fetchRequest.predicate) {
if (self.debug) NSLog(#"[%# %#] fetching %# with predicate: %#", NSStringFromClass([self class]), NSStringFromSelector(_cmd), self.fetchedResultsController.fetchRequest.entityName, self.fetchedResultsController.fetchRequest.predicate);
} else {
if (self.debug) NSLog(#"[%# %#] fetching all %# (i.e., no predicate)", NSStringFromClass([self class]), NSStringFromSelector(_cmd), self.fetchedResultsController.fetchRequest.entityName);
}
NSError *error;
[self.fetchedResultsController performFetch:&error];
if (error) NSLog(#"[%# %#] %# (%#)", NSStringFromClass([self class]), NSStringFromSelector(_cmd), [error localizedDescription], [error localizedFailureReason]);
} else {
if (self.debug) NSLog(#"[%# %#] no NSFetchedResultsController (yet?)", NSStringFromClass([self class]), NSStringFromSelector(_cmd));
}
[self.tableView reloadData];
}
- (void)setFetchedResultsController:(NSFetchedResultsController *)newfrc
{
NSFetchedResultsController *oldfrc = _fetchedResultsController;
if (newfrc != oldfrc) {
_fetchedResultsController = newfrc;
newfrc.delegate = self;
if ((!self.title || [self.title isEqualToString:oldfrc.fetchRequest.entity.name]) && (!self.navigationController || !self.navigationItem.title)) {
self.title = newfrc.fetchRequest.entity.name;
}
if (newfrc) {
if (self.debug) NSLog(#"[%# %#] %#", NSStringFromClass([self class]), NSStringFromSelector(_cmd), oldfrc ? #"updated" : #"set");
[self performFetch];
} else {
if (self.debug) NSLog(#"[%# %#] reset to nil", NSStringFromClass([self class]), NSStringFromSelector(_cmd));
[self.tableView reloadData];
}
}
}
#pragma mark - UITableViewDataSource
- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
if (self.debug) NSLog(#"fetchedResultsController returns %d sections", [[self.fetchedResultsController sections] count]);
return [[self.fetchedResultsController sections] count];
}
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
return [[[self.fetchedResultsController sections] objectAtIndex:section] numberOfObjects];
}
- (NSString *)tableView:(UITableView *)tableView titleForHeaderInSection:(NSInteger)section
{
return [[[self.fetchedResultsController sections] objectAtIndex:section] name];
}
- (NSInteger)tableView:(UITableView *)tableView sectionForSectionIndexTitle:(NSString *)title atIndex: (NSInteger)index
{
return [self.fetchedResultsController sectionForSectionIndexTitle:title atIndex:index];
}
- (NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView
{
return [self.fetchedResultsController sectionIndexTitles];
}
#pragma mark - NSFetchedResultsControllerDelegate
- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller
{
if (!self.suspendAutomaticTrackingOfChangesInManagedObjectContext)
{
[self.tableView beginUpdates];
self.beganUpdates = YES;
}
}
- (void)controller:(NSFetchedResultsController *)controller
didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
atIndex:(NSUInteger)sectionIndex
forChangeType:(NSFetchedResultsChangeType)type
{
if (!self.suspendAutomaticTrackingOfChangesInManagedObjectContext)
{
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
{
if(self.debug) NSLog(#"controller didChangeObject: %#", anObject);
if (!self.suspendAutomaticTrackingOfChangesInManagedObjectContext)
{
NSLog(#"#########Controller did change type: %d", type);
switch(type)
{
case NSFetchedResultsChangeInsert:
[self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeDelete:
[self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeUpdate:
[self.tableView reloadRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeMove:
[self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
[self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
}
}
}
- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller
{
if (self.beganUpdates) [self.tableView endUpdates];
if (self.debug) NSLog(#"controller Did Change Content");
}
- (void)endSuspensionOfUpdatesDueToContextChanges
{
_suspendAutomaticTrackingOfChangesInManagedObjectContext = NO;
}
- (void)setSuspendAutomaticTrackingOfChangesInManagedObjectContext:(BOOL)suspend
{
if (suspend) {
_suspendAutomaticTrackingOfChangesInManagedObjectContext = YES;
} else {
[self performSelector:#selector(endSuspensionOfUpdatesDueToContextChanges) withObject:0 afterDelay:0];
}
}
#end
And here's my specific view controller I subclassed from it:
- (NSArray *)sectionHeaderTitles
{
if (_sectionHeaderTitles == nil) _sectionHeaderTitles = [NSArray arrayWithObjects:#"Not Yet Uploaded", #"Uploaded But Not Featured", #"Previously Featured", nil];
return _sectionHeaderTitles;
}
- (NSDictionary *)selectedEntry
{
if (_selectedEntry == nil) _selectedEntry = [[NSDictionary alloc] init];
return _selectedEntry;
}
- (void)setupFetchedResultsController
{
[self.photoDatabase.managedObjectContext setStalenessInterval:0.0];
[self.photoDatabase.managedObjectContext.parentContext setStalenessInterval:0.0];
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:#"Animal"];
request.sortDescriptors = [NSArray arrayWithObjects:[NSSortDescriptor sortDescriptorWithKey:#"status" ascending:YES], [NSSortDescriptor sortDescriptorWithKey:#"unique" ascending:NO], nil];
self.fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request managedObjectContext:self.photoDatabase.managedObjectContext sectionNameKeyPath:#"status" cacheName:nil];
NSError *error;
BOOL success = [self.fetchedResultsController performFetch:&error];
if (!success) NSLog(#"error: %#", error);
else [self.tableView reloadData];
self.fetchedResultsController.delegate = self;
}
- (void)useDocument
{
if (![[NSFileManager defaultManager] fileExistsAtPath:[self.photoDatabase.fileURL path]]) {
[self.photoDatabase saveToURL:self.photoDatabase.fileURL forSaveOperation:UIDocumentSaveForCreating completionHandler:^(BOOL success) {
[self setupFetchedResultsController];
}];
} else if (self.photoDatabase.documentState == UIDocumentStateClosed) {
[self.photoDatabase openWithCompletionHandler:^(BOOL success) {
[self setupFetchedResultsController];
}];
} else if (self.photoDatabase.documentState == UIDocumentStateNormal) {
[self setupFetchedResultsController];
}
}
- (void)setPhotoDatabase:(WLManagedDocument *)photoDatabase
{
if (_photoDatabase != photoDatabase) {
_photoDatabase = photoDatabase;
[self useDocument];
}
}
- (void)viewDidLoad
{
[super viewDidLoad];
UILabel *label = [[UILabel alloc] initWithFrame:CGRectZero];
label.backgroundColor = [UIColor clearColor];
label.font = [UIFont fontWithName:#"AmericanTypewriter" size:20];
label.shadowColor = [UIColor colorWithWhite:0.0 alpha:0.5];
label.textAlignment = UITextAlignmentCenter;
label.textColor = [UIColor whiteColor];
self.navigationItem.titleView = label;
label.text = self.navigationItem.title;
[label sizeToFit];
}
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
// Get CoreData database made if necessary
if (!self.photoDatabase) {
NSURL *url = [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject];
url = [url URLByAppendingPathComponent:#"Default Photo Database"];
self.photoDatabase = [[WLManagedDocument alloc] initWithFileURL:url];
NSLog(#"No existing photoDatabase so a new one was created from default photo database file.");
}
self.tableView.backgroundColor = [UIColor colorWithPatternImage:[UIImage imageNamed:#"DarkWoodBackGround.png"]];
}
- (void)syncWithServer
{
// This is done on the syncQ
// Start the activity indicator on the nav bar
dispatch_async(dispatch_get_main_queue(), ^{
[self.spinner startAnimating];
self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:self.spinner];
[[NSNotificationCenter defaultCenter] addObserver:self
selector:#selector(managedObjectContextDidSave:)
name:NSManagedObjectContextDidSaveNotification
object:self.photoDatabase.managedObjectContext.parentContext];
});
// Find new animals (status == 0)
NSFetchRequest *newAnimalsRequest = [NSFetchRequest fetchRequestWithEntityName:#"Animal"];
newAnimalsRequest.predicate = [NSPredicate predicateWithFormat:#"status == 0"];
NSError *error;
NSArray *newAnimalsArray = [self.photoDatabase.managedObjectContext.parentContext executeFetchRequest:newAnimalsRequest error:&error];
if ([newAnimalsArray count]) NSLog(#"There are %d animals that need to be uploaded.", [newAnimalsArray count]);
if (error) NSLog(#"fetchError: %#", error);
// Get the existing animals from the server
NSArray *parsedDownloadedAnimalsByPhoto = [self downloadedAllAnimalsFromWeb];
// In the parent context, insert downloaded animals into core data
for (NSDictionary *downloadedPhoto in parsedDownloadedAnimalsByPhoto) {
[Photo photoWithWebDataInfo:downloadedPhoto inManagedObjectContext:self.photoDatabase.managedObjectContext.parentContext];
// table will automatically update due to NSFetchedResultsController's observing of the NSMOC
}
// Upload the new animals if there are any
if ([newAnimalsArray count] > 0) {
NSLog(#"There are %d animals that need to be uploaded.", [newAnimalsArray count]);
for (Animal *animal in newAnimalsArray) {
// uploadAnimal returns a number that lets us know if it was accepted by the server
NSNumber *unique = [self uploadAnimal:animal];
if ([unique intValue] != 0) {
animal.unique = unique;
// uploadThePhotosOf returns a success BOOL if all 3 uploaded successfully
if ([self uploadThePhotosOf:animal]){
[self.photoDatabase.managedObjectContext performBlock:^{
animal.status = [NSNumber numberWithInt:1];
}];
}
}
}
}
[self.photoDatabase.managedObjectContext.parentContext save:&error];
if (error) NSLog(#"Saving parent context error: %#", error);
[self performUpdate];
// Turn the activity indicator off and replace the sync button
dispatch_async(dispatch_get_main_queue(), ^{
// Save the context
[self.photoDatabase saveToURL:self.photoDatabase.fileURL forSaveOperation:UIDocumentSaveForOverwriting completionHandler:^(BOOL success) {
if (success)
{
NSLog(#"Document was saved");
[self.photoDatabase.managedObjectContext processPendingChanges];
} else {
NSLog(#"Document was not saved");
}
}];
[self.spinner stopAnimating];
self.navigationItem.leftBarButtonItem = self.syncButton;
});
// Here it skips to the notification I got from saving the context so I can MERGE them
}
- (NSNumber *)uploadAnimal:(Animal *)animal
{
NSURL *uploadURL = [NSURL URLWithString:#"index.php" relativeToURL:self.remoteBaseURL];
NSString *jsonStringFromAnimalMetaDictionary = [animal.metaDictionary JSONRepresentation];
NSLog(#"JSONRepresentation of %#: %#", animal.namestring, jsonStringFromAnimalMetaDictionary);
ASIFormDataRequest *request = [ASIFormDataRequest requestWithURL:uploadURL];
[request setPostValue:jsonStringFromAnimalMetaDictionary forKey:#"newmeta"];
[request startSynchronous];
NSError *error = [request error];
NSString *response;
if (!error) {
response = [request responseString];
NSNumber *animalUnique = [(NSArray *)[response JSONValue]objectAtIndex:0];
return animalUnique;
} else {
response = [error description];
NSLog(#"%# got an error: %#", animal.namestring, response);
return [NSNumber numberWithInt:0];
}
}
- (BOOL)uploadThePhotosOf:(Animal *)animal
{
NSURL *uploadURL = [NSURL URLWithString:#"index.php" relativeToURL:self.remoteBaseURL];
int index = [animal.photos count];
for (Photo *photo in animal.photos) {
// Name the jpeg file
NSTimeInterval timeInterval = [NSDate timeIntervalSinceReferenceDate];
NSString *imageServerPath = [NSString stringWithFormat:#"%lf-Photo.jpeg",timeInterval];
// Update the imageServerPath
photo.imageURL = imageServerPath;
NSData *photoData = [[NSData alloc] initWithData:photo.image];
NSString *photoMeta = [photo.metaDictionary JSONRepresentation];
ASIFormDataRequest *request = [ASIFormDataRequest requestWithURL:uploadURL];
[request addPostValue:photoMeta forKey:#"newphoto"];
[request addData:photoData withFileName:imageServerPath andContentType:#"image/jpeg" forKey:#"filename"];
[request setUploadProgressDelegate:self.progressView];
[request startSynchronous];
NSLog(#"%# progress: %#", animal.namestring, self.progressView.progress);
NSString *responseString = [request responseString];
NSLog(#"uploadThePhotosOf:%# photo at placement: %d has responseString: %#", animal.namestring, [photo.placement intValue], responseString);
SBJsonParser *parser= [[SBJsonParser alloc] init];
NSError *error = nil;
id jsonObject = [parser objectWithString:responseString error:&error];
NSNumber *parsedPhotoUploadResponse = [(NSArray *)jsonObject objectAtIndex:0];
// A proper response is not 0
if ([parsedPhotoUploadResponse intValue] != 0) {
photo.imageid = parsedPhotoUploadResponse;
--index;
}
}
// If the index spun down to 0 then it was successful
int success = (index == 0) ? 1 : 0;
return success;
}
- (NSArray *)downloadedAllAnimalsFromWeb
{
NSURL *downloadURL = [NSURL URLWithString:#"index.php" relativeToURL:self.remoteBaseURL];
ASIFormDataRequest *request = [ASIFormDataRequest requestWithURL:downloadURL];
[request setPostValue:#"yes" forKey:#"all"];
request.tag = kGetHistoryRequest;
[request startSynchronous];
NSString *responseString = [request responseString];
NSLog(#"downloadedAllAnimalsFromWeb responseString: %#", responseString);
SBJsonParser *parser= [[SBJsonParser alloc] init];
NSError *error = nil;
id jsonObject = [parser objectWithString:responseString error:&error];
NSArray *parsedDownloadedResponseStringArray = [NSArray arrayWithArray:jsonObject];
return parsedDownloadedResponseStringArray;
}
- (void)performUpdate
{
NSManagedObjectContext * context = self.photoDatabase.managedObjectContext.parentContext;
NSSet * inserts = [context updatedObjects];
if ([inserts count])
{
NSError * error = nil;
NSLog(#"There were inserts");
if ([context obtainPermanentIDsForObjects:[inserts allObjects]
error:&error] == NO)
{
NSLog(#"BAM! %#", error);
}
}
[self.photoDatabase updateChangeCount:UIDocumentChangeDone];
}
- (void)managedObjectContextDidSave:(NSNotification *)notification
{
[[NSNotificationCenter defaultCenter] removeObserver:self name:NSManagedObjectContextDidSaveNotification object:self.photoDatabase.managedObjectContext.parentContext];
NSLog(#"userInfo from the notification: %#", [notification userInfo]);
// Main thread context
NSManagedObjectContext *context = self.fetchedResultsController.managedObjectContext;
SEL selector = #selector(mergeChangesFromContextDidSaveNotification:);
[context performSelectorOnMainThread:selector withObject:notification waitUntilDone:YES];
NSLog(#"ContextDidSaveNotification was sent. MERGED");
}
#pragma mark - Table view data source
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:#"EntryCell"];
if (!cell) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"EntryCell"];
}
// Configure the cell here...
Animal *animal = [self.fetchedResultsController objectAtIndexPath:indexPath];
cell.textLabel.text = animal.namestring;
if (([animal.numberofanimals intValue] > 0) && animal.species) {
cell.detailTextLabel.text = [NSString stringWithFormat:#"%#s", animal.species];
} else {
cell.detailTextLabel.text = animal.species;
}
return cell;
}
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
NSIndexPath *indexPath = [self.tableView indexPathForCell:sender];
Animal *animal = [self.fetchedResultsController objectAtIndexPath:indexPath];
// be somewhat generic here (slightly advanced usage)
// we'll segue to ANY view controller that has a photographer #property
if ([segue.identifier isEqualToString:#"newAnimal"]) {
NSLog(#"self.photodatabase");
[(NewMetaEntryViewController *)[segue.destinationViewController topViewController] setPhotoDatabaseContext:self.photoDatabase.managedObjectContext];
} else if ([segue.destinationViewController respondsToSelector:#selector(setAnimal:)]) {
// use performSelector:withObject: to send without compiler checking
// (which is acceptable here because we used introspection to be sure this is okay)
[segue.destinationViewController performSelector:#selector(setAnimal:) withObject:animal];
NSLog(#"animal: %# \r\n indexPath: %#", animal, indexPath);
}
}
- (CGFloat)tableView:(UITableView *)tableView heightForHeaderInSection:(NSInteger)section
{
return 30;
}
- (NSArray *)sectionIndexTitlesForTableView:(UITableView *)tableView
{
return nil;
}
- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section
{
NSLog(#"header for section called for section: %d", section);
NSLog(#"fetchedResultsController sections: %#", self.fetchedResultsController.sections);
CGRect headerRect = CGRectMake(0, 0, tableView.bounds.size.width, 30);
UIView *header = [[UIView alloc] initWithFrame:headerRect];
UILabel *headerTitleLabel = [[UILabel alloc] initWithFrame:CGRectMake(5, 5, tableView.bounds.size.width - 10, 20)];
if ([(Animal *)[[[[self.fetchedResultsController sections] objectAtIndex:section] objects] objectAtIndex:0] status] == [NSNumber numberWithInt:0]) {
headerTitleLabel.text = [self.sectionHeaderTitles objectAtIndex:0];
} else if ([(Animal *)[[[[self.fetchedResultsController sections] objectAtIndex:section] objects] objectAtIndex:0] status] == [NSNumber numberWithInt:1]) {
headerTitleLabel.text = [self.sectionHeaderTitles objectAtIndex:1];
} else {
headerTitleLabel.text = [self.sectionHeaderTitles objectAtIndex:2];
}
headerTitleLabel.textColor = [UIColor whiteColor];
headerTitleLabel.font = [UIFont fontWithName:#"AmericanTypewriter" size:20];
headerTitleLabel.backgroundColor = [UIColor clearColor];
headerTitleLabel.alpha = 0.8;
[header addSubview:headerTitleLabel];
return header;
}

Answer 1

Way too much code for anyone to want to wade through.
However, from a quick inspection, it looks like you are violating the MOC constraints. Specifically, you are accessing the parent context directly, and not from its own thread, either.
Typically, you would start a new thread, then create a MOC in that thread, make its parent be the MOC of the document. then do your stuff, and call save on the new MOC. It will then notify the parent, which should handle the updating.