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POPassing objects in CoreData
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copied!<p>I am using CoreData in my application and it is a one-to-many relationship, I have two entities called <code>folders</code> and <code>files</code>. So a folder can have many files. So my first view controller shows all folders and when clicked on each folder, I show the files present in it. </p> <p>Now all the folders and files present in it are created by user dynamically and are not coming from any database or from web server.</p> <p>Now I have one more view controller, which I open from app delegate, and here I want to show some files.</p> <p>I know that first we should pass the <code>managedObjectContext</code>, which will be declared in app delegate</p> <pre><code>ViewController *View = [[ViewController alloc]initWithNibName: @"ViewController" bundle:nil] View.managedObjectContext = self.managedObjectContext; </code></pre> <p>So if we just pass <code>managedObjectContext</code>, can we access the file entity objects, OR we have to pass file entity object also.</p> <p>Now as you know, I have two entities, called <code>Folder</code> and <code>File</code>, now to access files stored in any folder, I just do this.</p> <pre><code>NSMutableArray *filesArray = [self.folder.file mutableCopy]; </code></pre> <p>But now, I want to show the files in anyView I want, which can be opened after two three navigations or it is opened directly from appDelegate.m.</p> <p>To be very clear , my question is how to do this? i.e how can I get filesArray from <code>AppDelegate</code>.</p> <p>Based on Below Answer edited. I have created a fetchResultsController this way </p> <pre><code>- (NSFetchedResultsController *)fetchedResultsController { if (m_fetchResultsController != nil) { return m_fetchResultsController; } NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; // Edit the entity name as appropriate. NSEntityDescription *entity = [NSEntityDescription entityForName:@"File" 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:@"alarm" ascending:YES]; NSArray *sortDescriptors = [NSArray arrayWithObjects:sortDescriptor, nil]; [fetchRequest setSortDescriptors:sortDescriptors]; [fetchRequest setPredicate:[NSPredicate predicateWithFormat:@"alarm!= nil"]]; // 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:nil cacheName:nil]; aFetchedResultsController.delegate = self; self.fetchResultsController = aFetchedResultsController; NSError *error = nil; if (![self.fetchResultsController performFetch:&error]) { // Replace this implementation with code to handle the error appropriately. // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. NSLog(@"Unresolved error %@, %@", error, [error userInfo]); abort(); } return m_fetchResultsController; } </code></pre> <p>and in ViewDidLoad and I written this way </p> <pre><code>- (void)viewDidLoad { [super viewDidLoad]; NSError *error; if (![[self fetchedResultsController] performFetch:&error]) { // Update to handle the error appropriately. NSLog(@"Unresolved error %@, %@", error, [error userInfo]); exit(-1); // Fail } NSMutableArray *alarms = [[self.fetchResultsController fetchedObjects]mutableCopy]; NSLog(@"alarmsCount:%d",[alarms count]); } </code></pre> <p>Regards Ranjit.</p>

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