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• Out-Of-Memory while doing Core Data migration

  - by Kamchatka

  Hello, I'm migrating a CoreData model between two versions of an application. I was storing binary data as blobs in the previous version and I want to take them out of the blobs for performance. My issue is that during the migration it seems that Core Data loads everything into memory which leads to Low Memory Warnings and then to my app being killed. Apple documentation suggests the following : http://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/CoreDataVersioning/Articles/vmCustomizingTheProcess.html#//apple_ref/doc/uid/TP40005510-SW9 However, it seems to rely on the fact that the large objects are applied different mapping. In my case, all the objects are basically the same and the same mapping has to be applied to each of them. I don't see in this case how I could apply their technique. How should I handle a migration with very large objects ?

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• UITableView with Core Data and fetchedResultsController - don't want to call it at start up

  - by zebulon

  Hi all, I started with the Navigation-based application. I have a UITableView that shows the content fetched from CoreData - using the - (NSFetchedResultsController *)fetchedResultsController from the template. The thing is that I don't want to fill the TableView with the results at the start-up, instead I want to fill the TableView with the results from a search. In my app I have an UITextField, where the user can type a string. And from that string, using predicate, I want to fill the UITableView with the results. In other words, at start-up, the UITableView should be empty and later filled with the search-results. Does anyone have an idea on how to accomplish this? Thanks in advance! EDIT: Solved it by moving out if (![fetchedResultsController_ performFetch:&error]) { and calling it later. I feel a bit stupid ;)

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• Delete NSManageObject at the event tableView:commiteEditingStyle:forRowAtIndexPath:

  - by David.Chu.ca

  I got exception when I tried to delete one NSManageObject at the event of tableView:commiteEditingStyle:forRowAtIndexPath:. Here is the part of my codes: - (void)tableView:(..)tableView commitEditingStyle:(..)editingStyle forRowAtIndexPath:(..)indexPath { if (editingStyle == UITableViewCellEditingStyleDelete) { [managedObjectContext deleteObject: [fetchedResultController objectAtIndexPath:indexPath]]; ... } } The exception was thrown at the line of deleteObject:(method of my local NSManagedObjectContext). This is the exception message: uncaught exception 'NSObjectInaccessibleException', reason: 'The NSManagedObject with ID:0x3d07a30 <x-coredata://0D2CC9CB-042B-496D-B3FE-5F1ED64EAB97/paymentType/p2> has been invalidated.' I tried to get entity object first and then to delete it. The entity looks OK but still the exception was at delete: NSManagedObject *entityToDelete = [fetchedResultsController objectAtIndexPath:indexPath]; [mangedObjectContext deleteObject:entityToDelete]; // Exception again. I am not sure if the entity object retrieved from the fetchedResultsController(NSFetchedResultsController type) cannot be deleted? If so, is there any other way to get the entity object for deleting?

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• Migrating a Core Data Store from iCloud to local

  - by schmok

  I'm currently struggling with Core Data iCloud migration. I want to move a store from an iCloud ubiquity container (.nosync) to a local URL. Problem is whenever I call something like this: NSPersistentStore *newStore = [self.persistentStoreCoordinator migratePersistentStore: currentiCloudStore toURL: localURL options: nil withType: NSSQLiteStoreType error: &error]; I get this error: -[NSPersistentStoreCoordinator addPersistentStoreWithType:configuration:URL:options:error:](1055): CoreData: Ubiquity: Error: A persistent store which has been previously added to a coordinator using the iCloud integration options must always be added to the coordinator with the options present in the options dictionary. If you wish to use the store without iCloud, migrate the data from the iCloud store file to a new store file in local storage. file://localhost/Users/sch/Library/Containers/bla/Data/Documents/tmp.sqlite. This will be a fatal error in a future release Anyone ever seen this error? Maybe I'm just missing the right migration options?

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• Tableview with sections managed by fetched results controller

  - by Matthes

  Hi, I'm quite new to CoreData and need help with one issue. I have tableview which simply lists cities stored in SQLite db. City is defined by "cityId" and "name" attributes. Data are fetched using NSFetchedResultsController and everything works fine except that I can't figure out how to make FetchedResultsController to group cities by first letter of city names. When I supply "name" for sectionNameKeyPath argument of initWithFetchRequest:managedObjectContext:sectionNameKeyPath:cacheName: method, it creates section for each city, which is obviously something I don't want. I can't figure out how to create an expression which would make it work in way I need. thanks for any tips and/or advices on this Matthes

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• Is this the correct way to reloadData on a UITableView?

  - by Sheehan Alam

  I am trying to append objects to my data source and then reload the table. Is this the correct way of approaching it? self.items is my datasource //Copy current items self.itemsCopy = [self.items mutableCopy];//[[NSMutableArray alloc] initWithArray:self.items copyItems:NO]; NSLog(@"Copy Size before append: %d",[itemsCopy count]); //Get new items int lastMsgID = [self getLastMessageID]; [self.coreData getMoreMessages:self.title lastID:lastMsgID]; //This will update self.items with 30 objects //Append new items [itemsCopy addObjectsFromArray:self.items]; //Empty items and copy itemsCopy [self.items removeAllObjects]; self.items = [self.itemsCopy mutableCopy]; NSLog(@"Actual Size after append: %d",[self.items count]); //Reload data [tableView reloadData];

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• iPad --- managedObject problem when [self.tableViewSection reloadData]

  - by user345777

  Hi , I am creating a news aggregator application that fetches a xml feed every 4 minutes. After the xml is loaded, I clear everything by deleting all the objects in the database, then save the new objects back into the database. I then call [self.tableViewSection reloadData]; to reload the tableView. Thats when I get a problem. As soon as the code gets to a section where i access the new [[managedObject valueForKey:@"event_text"] description] content it fails with a : * Terminating app due to uncaught exception 'NSObjectInaccessibleException', reason: 'CoreData could not fulfill a fault for '0x4b3f6a0 '' Now from the flow I described on top, it seems odd to me that the tableView is populated properly the next time i launch the application, with the "new" data I fetched in the previous session. So its not that data thats corrupt , but seems to me something goes wrong when I refetch the managedObject after saving new data. Also keep in mind thats this app runs fine on the iPhone, its the iPad thats is giving me this problem.

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• save UIImageView state & the save the Entire View

  - by adamprocter

  I have an iPad app where you add photos to a page. I then want to save the photos positions, then add further pages with more photo positions and eventually save all the pagesto be looked at later in a slideshow style. Can anyone advise 1. Saving UIImageView states when moving to new views (or swapping views) - I see this on using NSCoding iPhone - save UIImageView state - but am at a lose - any more examples ? 2. How to save the 'entire' set of view to look at later (like a slideshow) - no idea on where to start with this ? array ? coredata ? Thanks

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• Strategy for avoiding duplicate object ids for data shared across devices using iCloud

  - by rmaddy

  I have a data intensive iOS app that is not using CoreData nor does it support iCloud synching (yet). All of my objects are created with unique keys. I use a simple long long initialized with the current time. Then as I need a new key I increment the value by 1. This has all worked well for a few years with the app running isolated on a single device. Now I want to add support for automatic data sync across devices using iCloud. As my app is written, there is the possibility that two objects created on two different devices could end up with the same key. I need to avoid this possibility. I'm looking for ideas for solving this issue. I have a few requirements that the solution must meet: 1) The key needs to remain a single integral data type. Converting all existing keys to a compound key or to a string or other type would affect the entire code base and likely result in more bugs than it's worth. 2) The solution can't depend on an Internet connection. A user must be able to run the app and add data even with no Internet connection. The data should still resolve properly later when the data syncs through iCloud once a connection is available. I'll accept one exception to this rule. If no other option is available, I may be open to requiring an Internet connection the first time the app's data is initialized. One idea I have been toying around with in my head is logically splitting the integer key into two parts. The high 4 or 5 bits could be used as some sort of device id while the rest represents the actual key. The fuzzy part is figuring out how to come up with non-conflicting device ids that fit in a few bits. This should be viable since I don't need to deal will millions of devices. I just need to deal with the few devices that would be shared by a given iCloud account. I'm open to suggestions. Thanks.

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• How do I fix a corrupt calendar cache?

  - by Blacklight Shining

  I was tailing /var/log/system.log and noticed a sudden wall of text. Looking closer, I saw it was an error CalendarAgent got while trying to save something: Nov 18 11:42:45 rainbow-dash.local CalendarAgent[12321]: CoreData: error: (11) Fatal error. The database at /Users/blackl/Library/Calendars/Calendar Cache is corrupted. SQLite error code:11, 'database disk image is malformed' Nov 18 11:42:45 rainbow-dash.local CalendarAgent[12321]: Core Data: annotation: -executeRequest: encountered exception = Fatal error. The database at /Users/blackl/Library/Calendars/Calendar Cache is corrupted. SQLite error code:11, 'database disk image is malformed' with userInfo = { NSFilePath = "/Users/blackl/Library/Calendars/Calendar Cache"; NSSQLiteErrorDomain = 11; } 2 messages repeated several times Nov 18 11:42:49 rainbow-dash.local CalendarAgent[12321]: [com.apple.calendar.store.log.subscription] [WARNING: CalSubscriptionSession :: persistError :: save failed] This entire sequence is repeated many times throughout the log. file said the file in question was a SQLite 3.x database, so I did a bit of searching and came up with a way to check those. blackl% cp -i ~/Library/Calendars/Calendar\ Cache /tmp blackl% sqlite3 /tmp/Calendar\ Cache SQLite version 3.7.12 2012-04-03 19:43:07 Enter ".help" for instructions Enter SQL statements terminated with a ";" sqlite> pragma integrity_check ; *** in database main *** Main freelist: Bad ptr map entry key=863 expected=(2,0) got=(5,21) On page 21 at right child: 2nd reference to page 863 This is followed by a few dozen lines like these: rowid <number> missing from index <name> and then: wrong # of entries in index <name> I'm at a bit of a loss as to what to do now—I couldn't find anything on how to fix the errors that I found. Also, it would probably be a good idea to disable Calendar Agent so it doesn't try to use the database while it's being fixed (that's why I copied it to /tmp before running sqlite3 on it.) How do I disable CalendarAgent and fix its cache?

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• Add a row to UITableView for adding new item?

  - by David.Chu.ca

  In order to provide UI for user to add new items to my table view, I would like to add a new row in my table at a specified location (last row for example) when the view is in edit mode (I have a edit button on the view's navigation bar right side). This new row will have a add button indicator on the left side and disclosure accessory arrow on the right. When the view is not in edit mode, this add row should not be displayed. I am not sure if I should overwrite: - (void)setEditing:(BOOL)editing animated:(BOOL)animated{...} where I call the UITableView's method: insertRowsAtIndexPaths:(NSArray *)indexPaths withRowAnimation: (UITableViewRowAnimation)animation to insert a new row? My understanding is that this call may add a new row into the table view. The table view's data source is from CoreData storage. Not sure this may cause inconsistent numbers of data in the data store and table view? If it is OK and I have to manage rows in the table view, how can I add left add indicator and left disclosure arrow to the new row? Another question is that if I can do it to insert a new row as Add row, should I remove it when the table view not in edit mode? Just want to know if I am on the right track.

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• Why might changes be populated from one NSManagedObjectContext to another without an explicit merge?

  - by Mike Laurence

  I'm working on an object import feature that utilizes multiple threads/NSManagedObjectContexts, using http://www.mac-developer-network.com/columns/coredata/may2009/ as my guide (note that I am developing for iPhone). For some reason, when I save one of my contexts the other is immediately updated with the changes, even though I have commented out my calls to mergeChangesFromContextDidSaveNotification. Are there any reasons the contexts might be merging into one another without an explicit call? Here a log of what's going on: // 1.) Main context is saved with "Peter Gabriel" // 2.) Test context is created, begins with same contents as main context // 3.) Main context is inserted with "Spoon" // 4.) Test context is inserted with "Phoenix" // Contents at this point: CoreTest[4341:903] Artists in main context: ( "Peter Gabriel", "Spoon" ) CoreTest[4341:903] Artists in test context: ( "Peter Gabriel", "Phoenix" ) // 5.) testContext is saved // New contents of contexts: CoreTest[4341:903] Artists in main context: ( "Peter Gabriel", "Phoenix", "Spoon" ) CoreTest[4341:903] Artists in test context: ( "Peter Gabriel", "Phoenix" ) As you can see, the test context is saved midway through, and the main context suddenly has the new objects from the test context, even though I haven't performed the whole NSManagedObjectContextDidSaveNotification/mergeChangesFromContext combo. My understanding is that no changes will ever be merged unless done so explicitly... does anyone know what's going on here?

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• App freezing after lunch without any Error on Iphone Simulator?

  - by Meko

  HI.I am using CoreData on my UITable to show some records.It works when I first run.But if I run my app on simulator second time it shows up with data but then it stops.Sometimes it quits from app or it only froze and i cant click on table or tab bar. I looked also on Console but I thought there is no error.Here output from console The Debugger has exited with status 0. [Session started at 2010-03-30 00:22:06 +0300.] 2010-03-30 00:22:08.660 Paparazzi2[3556:207] Creating Photo: Urban disaster 2010-03-30 00:22:08.661 Paparazzi2[3556:207] Person is: Josh 2010-03-30 00:22:08.665 Paparazzi2[3556:207] Person is: Josh 2010-03-30 00:22:08.665 Paparazzi2[3556:207] -- Person Exists : Josh-- 2010-03-30 00:22:08.719 Paparazzi2[3556:207] Creating Photo: Concrete pitch forks 2010-03-30 00:22:08.719 Paparazzi2[3556:207] Person is: Josh 2010-03-30 00:22:08.721 Paparazzi2[3556:207] Person is: Josh 2010-03-30 00:22:08.721 Paparazzi2[3556:207] -- Person Exists : Josh-- 2010-03-30 00:22:08.727 Paparazzi2[3556:207] Creating Photo: Leaves on fire 2010-03-30 00:22:08.728 Paparazzi2[3556:207] Person is: Al 2010-03-30 00:22:08.734 Paparazzi2[3556:207] Person is: Al 2010-03-30 00:22:08.734 Paparazzi2[3556:207] -- Person Exists : Al-- [Session started at 2010-03-30 00:22:08 +0300.] GNU gdb 6.3.50-20050815 (Apple version gdb-967) (Tue Jul 14 02:11:58 UTC 2009) Copyright 2004 Free Software Foundation, Inc. GDB is free software, covered by the GNU General Public License, and you are welcome to change it and/or distribute copies of it under certain conditions. Type "show copying" to see the conditions. There is absolutely no warranty for GDB. Type "show warranty" for details. This GDB was configured as "i386-apple-darwin".sharedlibrary apply-load-rules all Attaching to process 3556. (gdb)

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• UiPickerView change font color according data

  - by Fulkron

  I'm using a pickerView with multiple components related to several fields in a Database (CoreData). Is it possible to change the fontcolor for a specific component according the presence of data in the DB ? For example the field in the DB is null the component font color should be RED otherwise black. Any help will be appreciated ! Dario ================== Thanks Kenny, I have to apply to a single UIPicker only. So I', returning the view parametere (without modificatiosn). The result is all the pickers show empty rows. Thanks for help ! Here you will find the code fragment: - (UIView *)pickerView:(UIPickerView *)pickerView viewForRow:(NSInteger)row forComponent:(NSInteger)component reusingView:(UIView *)view { if (pickerView == tipoPk){ UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(0, 0, 100,30)]; label.textColor = [UIColor redColor]; switch (component) { case PK_Tipo: label.text = [tipoArray objectAtIndex:row]]; break; case PK_Settore: label.text = [settoreArray objectAtIndex:row]]; break; default: break; } return label; } else { return view; // <==== return view for non related pickerviews , but no rows shown } }

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• Removing and adding persistent stores to a core data application

  - by mkko

  I'm using core data on an iPhone application. I have multiple persisntent stores that I'm switching from one to another so that only one of the stores can be active at the time. I have one managed object context and the different persistent stores are similar in data format (sqlite) and share the same managed object model. I'm importing the data to each persistent store from a respective XML file. For the first import everything works fine, but after I remove the imported data (the persistent store and the physical file) and then re-import, core data gives me an error: *** Terminating app due to uncaught exception 'NSObjectInaccessibleException', reason: 'The NSManagedObject with ID:0x3c14e00 <x-coredata://6D14F11E-2EA7-4141-9BE8-53747DE6FCC6/Book/p2> has been invalidated.' This error comes from the save: of NSManagedObjectContext. Before re-importing, i'm removing the persistent store from the persistent store coordinator and removing the physical file, so everything should be as if re-importing was done for the first time. Alos, the objects in managed object context are removed and the context is sent the reset: message (I don't know if this is actually needed). Could some one help me out here? How should the persistent store be switched? I'm basically using the same logic as tutored here: http://blog.sallarp.com/iphone-core-data-uitableview-drill-down/ Thanks in advance.

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• Delete NSManageObject at the event tableView:commitEditingStyle:forRowAtIndexPath:

  - by David.Chu.ca

  I got exception when I tried to delete one NSManageObject at the event of tableView:commitEditingStyle:forRowAtIndexPath:. Here is the part of my codes: - (void)tableView:(..)tableView commitEditingStyle:(..)editingStyle forRowAtIndexPath:(..)indexPath { if (editingStyle == UITableViewCellEditingStyleDelete) { [managedObjectContext deleteObject: [fetchedResultController objectAtIndexPath:indexPath]]; ... } } The exception was thrown at the line of deleteObject:(method of my local NSManagedObjectContext). This is the exception message: uncaught exception 'NSObjectInaccessibleException', reason: 'The NSManagedObject with ID:0x3d07a30 <x-coredata://0D2CC9CB-042B-496D-B3FE-5F1ED64EAB97/paymentType/p2> has been invalidated.' I tried to get entity object first and then to delete it. The entity looks OK but still the exception was at delete: NSManagedObject *entityToDelete = [fetchedResultsController objectAtIndexPath:indexPath]; [mangedObjectContext deleteObject:entityToDelete]; // Exception again. I am not sure if the entity object retrieved from the fetchedResultsController(NSFetchedResultsController type) cannot be deleted? If so, is there any other way to get the entity object for deleting? I found that in the Apple's Core Data Tutorial for iPhone with events example, there is on NSArray to hold event entity objects. I am not sure if that's necessory to use NSArray to hold my local entity objects and then use it for deleting?

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• Objective-C: fetchManagedObjectsForEntity problem

  - by Meko

  Hi.I am trying to get value from CoreData entity name Person with predicate and then comparing with new data in dictionary.But it it returns every time 0 .And it creates about 5 person with same name. NSPredicate *predicate = [NSPredicate predicateWithFormat:@"userName == %@",[flickr usernameForUserID:@"owner"]]; peopleList = (NSMutableArray *)[flickr fetchManagedObjectsForEntity:@"Person" withPredicate:predicate]; NSEnumerator *enumerator = [peopleList objectEnumerator]; Person *person; BOOL exists = FALSE; while (person = [enumerator nextObject]) { NSLog(@" Person is: %@ ", person.userName); NSLog(@"Person ID IS %@",person.userID); NSLog(@"Dict ID is %@",[dict objectForKey:@"owner"]); if([person.userID isEqualToString:[dict objectForKey:@"owner"]]) { exists = TRUE; NSLog(@"-- Person Exists : %@--", person.userName); [newPhoto setPerson:person]; } } Here peopleList returns 0 and the enumerator also 0 and it does not use if and not comparing.In my entity I have Person and Photo entities.In Person I have userName and userID attributes and also one-to many relationship with Photo entity. I think problem in predicate but i cant figure out it .

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• Best strategy for synching data in iPhone app

  - by iamj4de

  I am working on a regular iPhone app which pulls data from a server (XML, JSON, etc...), and I'm wondering what is the best way to implement synching data. Criteria are speed (less network data exchange), robustness (data recovery in case update fails), offline access and flexibility (adaptable when the structure of the database changes slightly, like a new column). I know it varies from app to app, but can you guys share some of your strategy/experience? For me, I'm thinking of something like this: 1) Store Last Modified Date in iPhone 2) Upon launching, send a message like getNewData.php?lastModifiedDate=... 3) Server will process and send back only modified data from last time. 4) This data is formatted as so: <+><data id="..."></data></+> // add this to SQLite/CoreData <-><data id="..."></data></-> // remove this <%><data id="..."><attribute>newValue</attribute></data></%> // new modified value I don't want to make <+, <-, <%... for each attribute as well, because it would be too complicated, so probably when receive a <% field, I would just remove the data with the specified id and then add it again (assuming id here is not some automatically auto-incremented field). 5) Once everything is downloaded and updated, I will update the Last Modified Date field. The main problem with this strategy is: If the network goes down when I am updating something = the Last Modified Date is not yet updated = next time I relaunch the app, I will have to go through the same thing again. Not to mention potential inconsistent data. If I use a temporary table for update and make the whole thing atomic, it would work, but then again, if the update is too long (lots of data change), the user has to wait a long time until new data is available. Should I use Last-Modified-Date for each of the data field and update data gradually?

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• UICollectionView with one static cell and N dynamic ones from a fetchresultscontroller exception

  - by nflacco

  I'm trying to make a UITableView that shows a blog post and comments for that post. My setup is a tableview in storyboard with two dynamic prototype cells. The first cell is for the post and should never change. The second cell represents the 0 to N comments. My cellForRowAtIndexPath method shows the post cell properly, but fails to get the comment at the given index path (though if I comment out the fetch I get the appropriate number of comment cells with a green background that I set as a visual debug thing). let comment = fetchedResultController.objectAtIndexPath(indexPath) as Comment I get the following exception on this line: 2014-08-24 15:06:40.712 MessagePosting[21767:3266409] *** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[__NSArrayM objectAtIndex:]: index 1 beyond bounds [0 .. 0]' *** First throw call stack: ( 0 CoreFoundation 0x0000000101aa43e5 __exceptionPreprocess + 165 1 libobjc.A.dylib 0x00000001037f9967 objc_exception_throw + 45 2 CoreFoundation 0x000000010198f4c3 -[__NSArrayM objectAtIndex:] + 227 3 CoreData 0x00000001016e4792 -[NSFetchedResultsController objectAtIndexPath:] + 162 Section and cell setup: override func tableView(tableView: UITableView!, numberOfRowsInSection section: Int) -> Int { // #warning Incomplete method implementation. // Return the number of rows in the section. switch section { case 0: return 1 default: if let realPost:Post = post { return fetchedResultController.sections[0].numberOfObjects } else { return 0 } } } override func tableView(tableView: UITableView!, cellForRowAtIndexPath indexPath: NSIndexPath!) -> UITableViewCell! { switch indexPath.section { case 0: let cell = tableView.dequeueReusableCellWithIdentifier(postViewCellIdentifier, forIndexPath: indexPath) as UITableViewCell cell.backgroundColor = lightGrey if let realPost:Post = self.post { cell.textLabel.text = realPost.text } return cell default: let cell = tableView.dequeueReusableCellWithIdentifier(commentCellIdentifier, forIndexPath: indexPath) as UITableViewCell cell.backgroundColor = UIColor.greenColor() let comment = fetchedResultController.objectAtIndexPath(indexPath) as Comment // <---------------------------- :( cell.textLabel.text = comment.text return cell } } FRC: func controllerDidChangeContent(controller: NSFetchedResultsController!) { tableView.reloadData() } func getFetchedResultController() -> NSFetchedResultsController { fetchedResultController = NSFetchedResultsController(fetchRequest: taskFetchRequest(), managedObjectContext: managedObjectContext, sectionNameKeyPath: nil, cacheName: nil) return fetchedResultController } func taskFetchRequest() -> NSFetchRequest { if let realPost:Post = self.post { let fetchRequest = NSFetchRequest(entityName: "Comment") let sortDescriptor = NSSortDescriptor(key: "date", ascending: false) fetchRequest.predicate = NSPredicate(format: "post = %@", realPost) fetchRequest.sortDescriptors = [sortDescriptor] return fetchRequest } else { return NSFetchRequest(entityName: "") } }

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• Handle row deletion in UITableViewController

  - by Kamchatka

  Hello, I hava a UINavigationController. The first level is a UITableViewController, the second level just shows details on one of the items of the table view. In this detail view, I can delete the item. It deletes the underlying managed object. When I pop back to the view, I have a crash. I understand why, it's because I didn't update the cached array that contains the data. I looked at several tutorials and I don't exactly understand how am I supposed to handle deletion. Maybe I don't understand exactly where I should fetch the objects in the model. Should I do a query for every cellForRowAtIndexPath and take the item in the result at position indexPath.row? It doesn't look efficient. Should I check for changes somewhere and recache the whole query in an array. I would think CoreData would provide something more natural but I couldn't find it so far. Thanks in advance.

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• NSPredicate cause update editing to return NSFetchedResultsChangeDelete not NSFetchedResultsChangeUp

  - by Matthew Weiss

  I have predicate inside of - (NSFetchedResultsController *)fetchedResultsController in a standard way starting from the CoreDataBook example. NSPredicate *predicate = [NSPredicate predicateWithFormat:@"state=%@ && date = %@ && date < %@", @"1",fromDate,toDate]; [fetchRequest setPredicate:predicate]; This works fine however when editing an item, it returns with NSFetchedResultsChangeDelete not Update. When the main view returns, it is missing the item. If I restart the simulator the delete was not saved and the correct editing result is shown the the predicate working correctly. case NSFetchedResultsChangeDelete: [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade]; break; I can confirm the behavior by commenting out the two predicate lines ONLY and then all works as it should correctly returning with the full set after editing and calling NSFetchedResultsChangeUpdate instead of NSFetchedResultsChangeDelete. I have read http://matteocaldari.it/2009/11/multiple-contexts-controllers-delegates-and-coredata-bug who reports similar behavior but I have not found a work around to my problem. I can

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• Objective-C subclass and base class casting

  - by ryanjm.mp

  I'm going to create a base class that implements very similar functions for all of the subclasses. This was answered in a different question. But what I need to know now is if/how I can cast various functions (in the base class) to return the subclass object. This is both for a given function but also a function call in it. (I'm working with CoreData by the way) As a function within the base class (this is from a class that is going to become my subclass) +(Structure *)fetchStructureByID:(NSNumber *)structureID inContext:(NSManagedObjectContext *)managedObjectContext {...} And as a function call within a given function: Structure *newStructure = [Structure fetchStructureByID:[currentDictionary objectForKey:@"myId"]]; inContext:managedObjectContext]; Structure is one of my subclasses, so I need to rewrite both of these so that they are "generic" and can be applied to other subclasses (whoever is calling the function). How do I do that? Update: I just realized that in the second part there are actually two issues. You can't change [Structure fetch...] to [self fetch...] because it is a class method, not an instance method. How do I get around that too?

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• Core Data: Deleting causes 'NSObjectInaccessibleException' from NSOperation with a reference to a deleted object

  - by Bryan Irace

  My application has NSOperation subclasses that fetch and operate on managed objects. My application also periodically purges rows from the database, which can result in the following race condition: An background operation fetches a bunch of objects (from a thread-specific context). It will iterate over these objects and do something with their properties. A bunch of rows are deleted in the main managed object context. The background operation accesses a property on an object that was deleted from the main context. This results in an 'NSObjectInaccessibleException', reason: 'CoreData could not fulfill a fault' Ideally, the objects that are fetched by the NSOperation can be operated on even if one is deleted in the main context. The best way I can think to achieve this is either to: Call [request setReturnsObjectsAsFaults:NO] to ensure that Core Data won't try to fulfill a fault for an object that no longer exists in the main context. The problem here is I may need to access the object's relationships, which (to my understanding) will still be faulted. Iterate through the managed objects up front and copy the properties I will need into separate non-managed objects. The problem here is that (I think) I will need to synchronize/lock this part, in case an object is deleted in the main context before I can finish copying. Am I missing something obvious? It doesn't seem like what I'm trying to accomplish is too out of the ordinary. Thanks for your help.

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• Fetch Data using predicate. Retrieve single value.

  - by Mr. McPepperNuts

  XYZAppDelegate *appDelegate = [[UIApplication sharedApplication] delegate]; NSManagedObjectContext *managedObjectContext = appDelegate.managedObjectContext; NSFetchRequest *request = [[NSFetchRequest alloc] init]; NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name == %@", entryToSearchFor]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"Entry" inManagedObjectContext:managedObjectContext]; NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:NO]; NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil]; [request setSortDescriptors:sortDescriptors]; [request setEntity: entity]; [request setPredicate: predicate]; NSArray *results = [managedObjectContext executeFetchRequest:request error:nil]; if (results == nil) { NSLog(@"No results found"); }else { NSLog(@"entryToSearchFor %@", entryToSearchFor); NSLog(@"results %@", [results objectAtIndex:0]); } I want to retrieve a single value (String) from "Entry." I believe I must be missing. Can someone point it out? Btw, the NSLog results outputs the following: results <NSManagedObject: 0x3d2d360> (entity: Entry; id: 0x3d13650 <x-coredata://6EA12ADA-8C0B-477F-801C-B44FE6E6C91C/Entry/p3> ; data: <fault>)

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• IOS : BAD ACCESS when trying to add a new Entity object

  - by Maverick447

  So i'm using coredata to model my relationships . This is the model in brief Type A can have one or more types of type B Type B has a inverse relationship of being associated with one of type A Type B can have one or more types of type C Type C has a inverse relationship of being associated with one of type B From a UI standpoint , I have a Navigation controller with controllers that successively sets up the first A object (VC-1) , then another viewcontroller (VC-2) creates a B object ( I pass in the A object to this controller) and the B object is added to the A object . Similarly the same thing happens with B and C . The third Viewcontroller (VC3) first creates a C object and assigns it to the passed B Object . Also between these viewcontrollers the managedObjectCOntext is also passed . SO my use case is such that while viewcontroller (VC-3) is the top controller a button action will keep creating multiple objects of type C and add them to the same type B object that was passed . Also as part of this function I save the managedObject context after saving each type C . e.g. code in viewcontroller 3 - (void) SaveNewTypeC { TypeC *newtypeC = (Question*)[NSEntityDescription insertNewObjectForEntityForName:@"TypeC" inManagedObjectContext:managedObjectContext]; [newtypeC setProp1:] ; [newtypeC setProp2:] .. .. **[typeBObject addTypeCInTypeBObject:newtypeC];** [section setTotalCObjectCount:[ NSNumber numberWithInt:typeCIndex++]]; NSError *error = nil; if (![managedObjectContext save:&error]) { // Handle error NSLog(@"Unresolved error %@, %@, %@", error, [error userInfo],[error localizedDescription]); exit(-1); // Fail } [newtypeC release]; } - (IBAction)selectedNewButton:(id)sender { [self SaveNewTypeC]; [self startRepeatingTimer]; } The BAD ACCESS seems to appear when the bold line above executes Relating to some HashValue . Any clues on resolving this would be helpful .

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