An ios11 application is crashing while saving to core data with a below exception, it is working fine in iOS10 and below.
Assertion failed: (moreParameters->mostRecentEntry == CFArrayGetValueAtIndex(stack, stackCount - 1)), function NSKeyValuePopPendingNotificationPerThread, file /BuildRoot/Library/Caches/com.apple.xbs/Sources/Foundation_Sim/Foundation-1444.12/EO.subproj/NSKeyValueObserving.m, line 933.
[context performBlockAndWait:^{
NSError *saveErr = nil;
if (![context save:&saveErr]) {
NSLog(#"Can't Save! %# %#", saveErr, [saveErr localizedDescription]);
}
}];
crash happening at if (![context save:&saveErr])
Below is NSManagedObject:
<ContentLanguage: 0x60000009f8b0> (entity: ContentLanguage; id: 0xd0000000000c0006 x-coredata://B53C7782-1231-4DB9-8579-77BFC31ADDA9/ContentLanguage/p3 ; data: {
displayName = "T\U00fcrk\U00e7e";
langId = tr;
relationship = "<relationship fault: 0x60400023c9e0 'relationship'>";
settings = nil;
user = "0xd000000000040002 x-coredata://B53C7782-1231-4DB9-8579-77BFC31ADDA9/User/p1";
})
ContentLanguage Entity
An app I'm building contains a catalogue of thousands of items, which need to be stored on the phone. Currently I am achieving this through CoreData, as logically it seemed like the best place to put it. I'm using GCD to run the CoreData insertion processes in the background and showing a progress bar / current percentage complete. This works as expected, however for only 5000 items, it's taking 8 minutes to complete on an iPhone 4. This application will be used on the 3GS and up, and will more likely contain 30/40 thousand items once it launches. Therefore this processing time is going to be horrifically long.
Is there any way I can use a CSV file or something to search through instead of storing each item in CoreData? I'm assuming there are some efficiency downfalls with an approach like this, but it would alleviate the excessive wait times. Unless there is another solution that would help with this problem.
Thanks.
EDIT:
I'm not sure how I'd go about saving the context at the end of the entire operation, as it uses a separate context within the loop. Any suggestions for this would be very much appreciated. I've got no idea how to progress with this.
Insertion Code Being Used
- (void) processUpdatesGCD {
NSArray *jsonArray=[NSJSONSerialization JSONObjectWithData:_responseData options:0 error:nil];
NSArray *products = [jsonArray valueForKey:#"products"];
NSArray *deletions;
if ([jsonArray valueForKey:#"deletions"] == (id)[NSNull null]){
self.totalCount = [products count];
} else {
deletions = [jsonArray valueForKey:#"deletions"];
self.totalCount = [products count] + [deletions count];
}
self.productDBCount = 0;
_delegate = [[UIApplication sharedApplication] delegate];
NSManagedObjectContext *managedObjectContext = _delegate.managedObjectContext;
self.persistentStoreCoordinator = [managedObjectContext persistentStoreCoordinator];
_managedObjectContext = managedObjectContext;
// Create a new background queue for GCD
dispatch_queue_t backgroundDispatchQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0);
for (id p in products) {
// id product = p;
// Dispatch the following code on our background queue
dispatch_async(backgroundDispatchQueue,
^{
id product = p;
// Because at this point we are running in another thread we need to create a
// new NSManagedContext using the app's persistance store coordinator
NSManagedObjectContext *backgroundThreadContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSConfinementConcurrencyType];
[backgroundThreadContext setPersistentStoreCoordinator:self.persistentStoreCoordinator];
NSFetchRequest *BGRequest = [[NSFetchRequest alloc] init];
NSLog(#"Running.. (%#)", product);
[BGRequest setEntity:[NSEntityDescription entityForName:#"Products" inManagedObjectContext:backgroundThreadContext]];
[BGRequest setIncludesSubentities:NO];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"codes == %#", [product valueForKey:#"product_codes"]];
[BGRequest setPredicate:predicate];
NSError *err;
NSArray *results = [backgroundThreadContext executeFetchRequest:BGRequest error:&err];
if (results.count == 0){
// Product doesn't exist with code, make a new product
NSLog(#"Product not found for add/update (%#)", [product valueForKey:#"product_name"]);
NSManagedObject* newProduct;
newProduct = [NSEntityDescription insertNewObjectForEntityForName:#"Products" inManagedObjectContext:backgroundThreadContext];
[newProduct setValue:[product valueForKey:#"product_name"] forKey:#"name"];
[newProduct setValue:[product valueForKey:#"product_codes"] forKey:#"codes"];
if ([product valueForKey:#"information"] == (id)[NSNull null]){
// No information, NULL
[newProduct setValue:#"" forKey:#"information"];
} else {
NSString *information = [product valueForKey:#"information"];
[newProduct setValue:information forKey:#"information"];
}
} else {
NSLog(#"Product found for add/update (%#)", [product valueForKey:#"product_name"]);
// Product exists, update existing product
for (NSManagedObject *r in results) {
[r setValue:[product valueForKey:#"product_name"] forKey:#"name"];
if ([product valueForKey:#"information"] == (id)[NSNull null]){
// No information, NULL
[r setValue:#"" forKey:#"information"];
} else {
NSString *information = [product valueForKey:#"information"];
[r setValue:information forKey:#"information"];
}
}
}
// Is very important that you save the context before moving to the Main Thread,
// because we need that the new object is writted on the database before continuing
NSError *error;
if(![backgroundThreadContext save:&error])
{
NSLog(#"There was a problem saving the context (add/update). With error: %#, and user info: %#",
[error localizedDescription],
[error userInfo]);
}
// Now let's move to the main thread
dispatch_async(dispatch_get_main_queue(), ^
{
// If you have a main thread context you can use it, this time i will create a
// new one
// NSManagedObjectContext *mainThreadContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSConfinementConcurrencyType];
// [mainThreadContext setPersistentStoreCoordinator:self.persistentStoreCoordinator];
self.productDBCount = self.productDBCount + 1;
float progress = ((float)self.productDBCount / (float)self.totalCount);
int percent = progress * 100.0f;
// NSNumber *progress = [NSNumber numberWithFloat:((float)self.productDBCount / (float)self.totalCount)];
self.downloadUpdateProgress.progress = progress;
self.percentageComplete.text = [NSString stringWithFormat:#"%i", percent];
NSLog(#"Added / updated product %f // ProductDBCount: %i // Percentage progress: %i // Total Count: %i", progress, self.productDBCount, percent, self.totalCount);
if (self.productDBCount == self.totalCount){
[self updatesCompleted:[jsonArray valueForKey:#"last_updated"]];
}
});
});
}
if ([deletions count] > 0){
for (id d in deletions){
dispatch_async(backgroundDispatchQueue,
^{
id deleted = d;
// Because at this point we are running in another thread we need to create a
// new NSManagedContext using the app's persistance store coordinator
NSManagedObjectContext *backgroundThreadContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSConfinementConcurrencyType];
[backgroundThreadContext setPersistentStoreCoordinator:self.persistentStoreCoordinator];
NSFetchRequest *BGRequest = [[NSFetchRequest alloc] init];
// NSLog(#"Running.. (%#)", deleted);
[BGRequest setEntity:[NSEntityDescription entityForName:#"Products" inManagedObjectContext:backgroundThreadContext]];
[BGRequest setIncludesSubentities:NO];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"codes == %#", [deleted valueForKey:#"product_codes"]];
[BGRequest setPredicate:predicate];
NSError *err;
NSArray *results = [backgroundThreadContext executeFetchRequest:BGRequest error:&err];
if (results.count == 0){
// Product doesn't exist with code, make a new product
NSLog(#"Product not found, can't delete.. %#", [deleted valueForKey:#"product_name"]);
} else {
NSLog(#"Product found, deleting: %#", [deleted valueForKey:#"product_name"]);
// Product exists, update existing product
for (NSManagedObject *r in results) {
[backgroundThreadContext deleteObject:r];
}
}
// Is very important that you save the context before moving to the Main Thread,
// because we need that the new object is writted on the database before continuing
NSError *error;
if(![backgroundThreadContext save:&error])
{
NSLog(#"There was a problem saving the context (delete). With error: %#, and user info: %#",
[error localizedDescription],
[error userInfo]);
}
// Now let's move to the main thread
dispatch_async(dispatch_get_main_queue(), ^
{
self.productDBCount = self.productDBCount + 1;
float progress = ((float)self.productDBCount / (float)self.totalCount);
int percent = progress * 100.0f;
// NSNumber *progress = [NSNumber numberWithFloat:((float)self.productDBCount / (float)self.totalCount)];
self.downloadUpdateProgress.progress = progress;
self.percentageComplete.text = [NSString stringWithFormat:#"%i", percent];
NSLog(#"Deleted product %f // ProductDBCount: %i // Percentage progress: %i // Total Count: %i", progress, self.productDBCount, percent, self.totalCount);
if (self.productDBCount == self.totalCount){
[self updatesCompleted:[jsonArray valueForKey:#"last_updated"]];
}
/*
*
* Change the completion changes to a method. Check to see if the total number of products == total count. If it does, run the completion method.
*
*/
});
});
}
}
}
Put the IF inside the dispatch, run one save at the end
// Create a new background queue for GCD
dispatch_queue_t backgroundDispatchQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0);
// id product = p;
// Dispatch the following code on our background queue
dispatch_async(backgroundDispatchQueue,
^{
NSManagedObjectContext *backgroundThreadContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSConfinementConcurrencyType];
[backgroundThreadContext setPersistentStoreCoordinator:self.persistentStoreCoordinator];
for (id p in products) {
id product = p;
// Because at this point we are running in another thread we need to create a
// new NSManagedContext using the app's persistance store coordinator
NSFetchRequest *BGRequest = [[NSFetchRequest alloc] init];
NSLog(#"Running.. (%#)", product);
[BGRequest setEntity:[NSEntityDescription entityForName:#"Products" inManagedObjectContext:backgroundThreadContext]];
[BGRequest setIncludesSubentities:NO];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"codes == %#", [product valueForKey:#"product_codes"]];
[BGRequest setPredicate:predicate];
NSError *err;
NSArray *results = [backgroundThreadContext executeFetchRequest:BGRequest error:&err];
if (results.count == 0){
// Product doesn't exist with code, make a new product
NSLog(#"Product not found for add/update (%#)", [product valueForKey:#"product_name"]);
NSManagedObject* newProduct;
newProduct = [NSEntityDescription insertNewObjectForEntityForName:#"Products" inManagedObjectContext:backgroundThreadContext];
[newProduct setValue:[product valueForKey:#"product_name"] forKey:#"name"];
[newProduct setValue:[product valueForKey:#"product_codes"] forKey:#"codes"];
if ([product valueForKey:#"information"] == (id)[NSNull null]){
// No information, NULL
[newProduct setValue:#"" forKey:#"information"];
} else {
NSString *information = [product valueForKey:#"information"];
[newProduct setValue:information forKey:#"information"];
}
} else {
NSLog(#"Product found for add/update (%#)", [product valueForKey:#"product_name"]);
// Product exists, update existing product
for (NSManagedObject *r in results) {
[r setValue:[product valueForKey:#"product_name"] forKey:#"name"];
if ([product valueForKey:#"information"] == (id)[NSNull null]){
// No information, NULL
[r setValue:#"" forKey:#"information"];
} else {
NSString *information = [product valueForKey:#"information"];
[r setValue:information forKey:#"information"];
}
}
}
// Is very important that you save the context before moving to the Main Thread,
// because we need that the new object is writted on the database before continuing
// Now let's move to the main thread
dispatch_async(dispatch_get_main_queue(), ^
{
// If you have a main thread context you can use it, this time i will create a
// new one
// NSManagedObjectContext *mainThreadContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSConfinementConcurrencyType];
// [mainThreadContext setPersistentStoreCoordinator:self.persistentStoreCoordinator];
self.productDBCount = self.productDBCount + 1;
float progress = ((float)self.productDBCount / (float)self.totalCount);
int percent = progress * 100.0f;
// NSNumber *progress = [NSNumber numberWithFloat:((float)self.productDBCount / (float)self.totalCount)];
self.downloadUpdateProgress.progress = progress;
self.percentageComplete.text = [NSString stringWithFormat:#"%i", percent];
NSLog(#"Added / updated product %f // ProductDBCount: %i // Percentage progress: %i // Total Count: %i", progress, self.productDBCount, percent, self.totalCount);
NSDate *currentProcessedDate = [NSDate date];
NSTimeInterval timeSinceStarted = [currentProcessedDate timeIntervalSinceDate:self.startProcessing];
NSInteger remainingProcesses = self.totalCount - self.productDBCount;
float timePerProcess = timeSinceStarted / (float)self.productDBCount;
float remainingTime = timePerProcess * (float)remainingProcesses;
self.timeRemaining.text = [NSString stringWithFormat:#"ETA: %0.0f minutes", fmodf(remainingTime, 60.0f)];
if (self.productDBCount == self.totalCount){
[self updatesCompleted:[jsonArray valueForKey:#"last_updated"]];
}
/*
*
* Change the completion changes to a method. Check to see if the total number of products == total count. If it does, run the completion method.
*
*/
});
}
NSError *error;
if(![backgroundThreadContext save:&error])
{
NSLog(#"There was a problem saving the context (add/update). With error: %#, and user info: %#",
[error localizedDescription],
[error userInfo]);
}
});
Ok, here's your problem.
Every time you insert a record, you do a save operation to the context.
Now, don't do it, that's what takes alot of time.
Do the save operation once, in the end of the loop, not every time you insert a record.
In your case I would check what is really time consuming?
Is it downloading data, is it importing data to CoreData?
Where do you get data from? Do you download it or you have it in Application Bundle?
CoreData is faster then CSV file. So it wont make your app faster.
Some tricks:
While importing data just save context at the end of the process. Do not save context in a loop.
If you do not need to download data and can put in the bundle, you can create coredata file in the simulator, put in the bundle and copy the file on first launch. It is really much more faster then importing data.
I've been working on adding Core Data into my iPhone app, and I've been running into some very frustrating issues. When I call save on my context, the save returns successfully, however no data is getting added to my database(I am running this on the simulator and looking at the SQLITE file to check).
I am using the MYDocumentHandler class from this post to use a single UIManagedDocument across multiple classes. I run the code in my AppDelegate as follows:
if (!self.document) {
[[MYDocumentHandler sharedDocumentHandler] performWithDocument:^(UIManagedDocument *document) {
self.document = document;
self.context = document.managedObjectContext;
[self loadView];
}];
}
The loadView method setups up my view controllers once the document has been returned. In my view controllers that use the Core Data I again use something like this:
- (void)viewDidLoad
{
[super viewDidLoad];
if(!self.document){
[[MYDocumentHandler sharedDocumentHandler] performWithDocument:^(UIManagedDocument *document) {
self.document = document;
self.context = document.managedObjectContext;
[self loadAll];
}];
}
}
Where the loadAll method setups everything for the view. When I try to save my data, I use the following:
for (int i = 0; i < [jsonArray count]; i++) {
NSDictionary *dictionary = [jsonArray objectAtIndex:i];
ProjectObject *tempProject = [[ProjectObject alloc] initWithDict:dictionary andETag:etag];
[tempAllProjects addObject:[Projects newProject:tempProject withContext:self.context]];
[tempProject release];
}
[self saveWithContext:self.context];
My saveWithContext method looks like this:
- (BOOL) saveWithContext:(NSManagedObjectContext *)context{
NSError *error = nil;
if (context != nil) {
if ([context hasChanges] && ![context save:&error]) {
DLog(#"Unresolved error %#, %#", error, [error userInfo]);
} else{
DLog(#"save was successful");
return YES;
}
}else{
DLog(#"context is nil");
return NO;
}
}
I always get the save was successful message, and I get the proper messages from the MYDocumentHandler file. Unfortunately, the data is simply not making it to the database. The data is definitely stored in the context, but its not going to the database. Any ideas?
Edit:
Here is the code where I create the Entities:
+ (Projects *) newProject:(ProjectObject *)project withContext:(NSManagedObjectContext *)context
{
Projects *newProject = nil;
NSFetchRequest *request = [NSFetchRequest fetchRequestWithEntityName:#"Projects"];
request.predicate = [NSPredicate predicateWithFormat:#"project_id = %#", project.project_id];
NSArray *results = [context executeFetchRequest:request error:nil];
NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
if([results count] > 0){
newProject = [results objectAtIndex:0];
newProject.account_id = [NSString stringWithFormat:#"%#", [defaults objectForKey:#"account_id"]];
} else {
newProject = [NSEntityDescription insertNewObjectForEntityForName:#"Projects" inManagedObjectContext:context];
}
newProject.account_id = [NSString stringWithFormat:#"%#", [defaults objectForKey:#"account_id"]];
newProject.project_id = project.project_id;
newProject.name = project.name;
newProject.project_description = project.description;
newProject.updated_at = project.updated_at;
newProject.starred = project.starred;
newProject.etag = project.etag;
newProject.synced = [self hasConnection] ? [NSNumber numberWithInt:1] : [NSNumber numberWithInt:0];
return newProject;
}
I found the solution in this post. Not sure if this is the best way to handle it. If there is a better option, please let me know.
You are not saving Manage object context after changing it. I have added the lines into your code.
Please check if it works now.
I’m missing the boat on something that I thought I had the hang of and was hoping someone here could help.
I’m using Xcode version 4.4 and my project is using Core Data, Storyboards and ARC.
My project has the following 3 entities.
All works well with the Livestock and Notes entities. But when I try to save data to the Taxonomy entity nothing happens. I get no error but the data is not saved.
Is it ok that I not use an array for the fetched results? Based on my predicate, I’m expecting only one object to be returned so I thought I didn’t need an array. Below is my code that does the saving. I have verified that data is being passed in from the view's text variables.
AppDelegate *appDelegate = (AppDelegate *) [[UIApplication sharedApplication] delegate];
NSManagedObjectContext *managedObjectContext = [appDelegate managedObjectContext];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
fetchRequest.entity = [NSEntityDescription entityForName:#"Livestock" inManagedObjectContext:managedObjectContext];
fetchRequest.predicate = [NSPredicate predicateWithFormat:#"tank == %# AND type == %# AND name == %#", self.detailTank, self.detailType, self.detailName];
NSError *error = nil;
Livestock *livestock = [[managedObjectContext executeFetchRequest:fetchRequest error:&error] lastObject];
if (error) {
NSLog(#"TaxonViewController: saveTaxonomy: Retrieving Livestock Record for saving: error = %#", error);
}
Taxonomy *taxonomy = livestock.taxonChildren;
taxonomy.kingdom = self.kingdom.text;
taxonomy.phylum = self.phylum.text;
taxonomy.classs = self.classs.text;
taxonomy.order = self.order.text;
taxonomy.family = self.family.text;
taxonomy.genus = self.genus.text;
taxonomy.species = self.species.text;
taxonomy.common = self.common.text;
taxonomy.livestockParent = livestock;
error = nil;
if (![managedObjectContext save:&error]) {
NSLog(#"Taxonomy save error. error = %#, userInfo = %#", error, [error userInfo]);
}
Any insight is greatly appreciated! Thanks!
UPDATE 1:
Modified code to test for NULL taxonChildren value. This solved it for me. Thanks Jesse!
if (livestock.taxonChildren == NULL) {
Taxonomy *taxonomy = [NSEntityDescription insertNewObjectForEntityForName:#"Taxonomy" inManagedObjectContext:managedObjectContext];
taxonomy.kingdom = self.kingdom.text;
taxonomy.phylum = self.phylum.text;
taxonomy.classs = self.classs.text;
taxonomy.order = self.order.text;
taxonomy.family = self.family.text;
taxonomy.genus = self.genus.text;
taxonomy.species = self.species.text;
taxonomy.common = self.common.text;
taxonomy.livestockParent = livestock;
}
else {
Taxonomy *taxonomy = livestock.taxonChildren;
taxonomy.kingdom = self.kingdom.text;
taxonomy.phylum = self.phylum.text;
taxonomy.classs = self.classs.text;
taxonomy.order = self.order.text;
taxonomy.family = self.family.text;
taxonomy.genus = self.genus.text;
taxonomy.species = self.species.text;
taxonomy.common = self.common.text;
taxonomy.livestockParent = livestock;
}
Is your livestock.taxonChildren nil? You'll have to insert an instance of that object into your context first; it won't create one automatically, even with a one-to-one relationship.
Note that you should not test for error like this:
if (error) { ... }
because error may be garbage when the fetch request is successful. You should instead test the return value:
NSArray *results = [managedObjectContext executeFetchRequest...]
if (!results) { ... }
I have this piece of code which I am using to update some values in Core Data when another object is added:
//Create new receipt
Receipt *receipt = [[Receipt alloc] init];
receipt.project = self.projectLabel.text;
receipt.amount = self.amountTextField.text;
receipt.descriptionNote = self.descriptionTextField.text;
receipt.business = self.businessNameTextField.text;
receipt.date = self.dateLabel.text;
receipt.category = self.categoryLabel.text;
receipt.paidBy = self.paidByLabel.text;
receipt.receiptImage1 = self.receiptImage1;
//Need to set this to 2
receipt.receiptImage2 = self.receiptImage1;
receipt.receiptNumber = #"99";
int count = 0;
int catCount = 0;
for (Project *p in appDelegate.projects)
{
if ([p.projectName isEqualToString:receipt.project]){
double tempValue = [p.totalValue doubleValue];
tempValue += [receipt.amount doubleValue];
NSString *newTotalValue = [NSString stringWithFormat:#"%.02f", tempValue];
NSString *newProjectName = p.projectName;
//remove entity from Core Data
NSFetchRequest * allProjects = [[NSFetchRequest alloc] init];
[allProjects setEntity:[NSEntityDescription entityForName:#"Project" inManagedObjectContext:appDelegate.managedObjectContext]];
[allProjects setIncludesPropertyValues:NO]; //only fetch the managedObjectID
NSError * error = nil;
NSArray * projectsArray = [appDelegate.managedObjectContext executeFetchRequest:allProjects error:&error];
//Delete product from Core Data
[appDelegate.managedObjectContext deleteObject:[projectsArray objectAtIndex:count]];
NSError *saveError = nil;
[appDelegate.managedObjectContext save:&saveError];
[appDelegate.projects removeObjectAtIndex:count];
NSLog(#"Removed project from Core Data");
//Insert a new object of type ProductInfo into Core Data
NSManagedObject *projectInfo = [NSEntityDescription
insertNewObjectForEntityForName:#"Project"
inManagedObjectContext:appDelegate.managedObjectContext];
//Set receipt entities values
[projectInfo setValue:newProjectName forKey:#"name"];
[projectInfo setValue:newTotalValue forKey:#"totalValue"];
if (![appDelegate.managedObjectContext save:&error]) {
NSLog(#"Whoops, couldn't save: %#", [error localizedDescription]);
}
NSLog(#"Added Project to Core Data");
Project *tempProject = [[Project alloc] init];
tempProject.projectName = [projectInfo valueForKey:#"name"];
tempProject.totalValue = [projectInfo valueForKey:#"totalValue"];
[appDelegate.projects addObject:tempProject];
}
count++;
}
for (Category *c in appDelegate.categories){
if ([c.categoryName isEqualToString:receipt.category]){
double tempValue = [c.totalValue doubleValue];
tempValue += [receipt.amount doubleValue];
NSString *newTotalValue = [NSString stringWithFormat:#"%.02f", tempValue];
NSString *newCategoryName = c.categoryName;
//remove entity from Core Data
NSFetchRequest * allCategories = [[NSFetchRequest alloc] init];
[allCategories setEntity:[NSEntityDescription entityForName:#"Category" inManagedObjectContext:appDelegate.managedObjectContext]];
[allCategories setIncludesPropertyValues:NO]; //only fetch the managedObjectID
NSError * categoriesError = nil;
NSArray * categoriesArray = [appDelegate.managedObjectContext executeFetchRequest:allCategories error:&categoriesError];
//Delete product from Core Data
[appDelegate.managedObjectContext deleteObject:[categoriesArray objectAtIndex:catCount]];
NSError *categorySaveError = nil;
[appDelegate.managedObjectContext save:&categorySaveError];
[appDelegate.categories removeObjectAtIndex:catCount];
NSLog(#"Removed category from Core Data");
NSError * error = nil;
//Insert a new object of type ProductInfo into Core Data
NSManagedObject *categoryInfo = [NSEntityDescription
insertNewObjectForEntityForName:#"Category"
inManagedObjectContext:appDelegate.managedObjectContext];
//Set receipt entities values
[categoryInfo setValue:newCategoryName forKey:#"name"];
[categoryInfo setValue:newTotalValue forKey:#"totalValue"];
if (![appDelegate.managedObjectContext save:&error]) {
NSLog(#"Whoops, couldn't save: %#", [error localizedDescription]);
}
NSLog(#"Added Category to Core Data");
Category *tempCategory = [[Category alloc] init];
tempCategory.categoryName = [categoryInfo valueForKey:#"name"];
tempCategory.totalValue = [categoryInfo valueForKey:#"totalValue"];
[appDelegate.categories addObject:tempCategory];
}
catCount++;
}
This code gives the error:
'...was mutated while being enumerated'.
Can anyone explain why? Also, is there a better approach to doing what I'm trying to achieve?
The error you're seeing is accurate. The problem is that you're mutating (changing) a collection while iterating over it. Basically, you're doing something of the form:
for (Project *p in appDelegate.projects) {
...
[p addObject: X]
}
This isn't allowed.
One simple solution is to make a new collection of the objects you want to add, and then add them to the original container outside of your loop. Something like:
NSMutableArray *array = [NSMutableArray array];
for (Project *p in appDelegate.projects) {
...
[array addObject:X];
}
[p addObjects:array];
By the way, did you google for the error text "was mutated while being enumerated"? I'd be surprised if you didn't find the answer for this common problem just by googling.
Also, when posting an error message, it's helpful to post the full line, not just part of it.
You are adding and removing items from appDelegate.projects while iterating over it in a for-each loop here:
[appDelegate.projects removeObjectAtIndex:count];
// ...
[appDelegate.projects addObject:tempProject];
And the same for appDelegate.categories:
[appDelegate.categories removeObjectAtIndex:count];
// ...
[appDelegate.categories addObject:tempProject];
AFAIK, in such case you should use a simple for loop, and access the array with index.