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POIOS How to sync multithreading NSManagedObjectContext?
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  1. POIOS How to sync multithreading NSManagedObjectContext?
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    copied!<p>Application must update data from WebService in loop each 10 sec in background and display data to user by his request in the main thread. Also I need update and delete records by user request. Updates done with runloop.</p> <p>I have registered notification in the AppDelegate</p> <pre><code> [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(contextChanged:) name:NSManagedObjectContextDidSaveNotification object:nil]; - (void)contextChanged:(NSNotification*)notification { if ([notification object] == [self managedObjectContext]) return; if (![NSThread isMainThread]) { [self performSelectorOnMainThread:@selector(contextChanged:) withObject:notification waitUntilDone:YES]; return; } [[self managedObjectContext] mergeChangesFromContextDidSaveNotification:notification]; [self saveContext]; //do I need this here or marge save data too? } </code></pre> <p>I have Storage sharedInstance class with </p> <pre><code>NSOperationQueue* operationQueue; </code></pre> <p>then inserts,updates,selects operators added this way from any thread:</p> <pre><code>-(void)do_something { [self.operationQueue addOperationWithBlock:^{ NSManagedObjectContext*moc; //creating new NSManagedObjectContext with AppDelegate.persistentStoreCoordinator //do my staff [moc save:&amp;error] }] } </code></pre> <p>The problem is when I try update entities with @"my_id=%@", @(my_id) </p> <pre><code>[moc countForFetchRequest:fetchRequest error:&amp;error] </code></pre> <p>return 0 and cause inserting of duplicate exists entity The problem is with synchronization. Advice please. should I use instance of dispatch_queue_create("com.my.", 0); instead for each CoreData operation?</p> <hr> <p>I did try remove operationQuiue</p> <pre><code>-(void)query:(void(^)(NSManagedObjectContext *context))queryBlock { NSLog(@"query CALL"); __block NSManagedObjectContext *context; //if remove dispatch_sync and/or run in main thread result the same dispatch_sync( dispatch_queue_create("com.myapp.db-queue", 0), ^{ AppDelegate*app = AppDelegate(); //same result if I use //app.persistentStoreCoordinator or //[app.managedObjectContext persistentStoreCoordinator] NSPersistentStoreCoordinator *persistentStoreCoordinator= [app.managedObjectContext persistentStoreCoordinator]; context = [NSManagedObjectContext new]; [context setPersistentStoreCoordinator:persistentStoreCoordinator]; [context setMergePolicy:NSMergeByPropertyStoreTrumpMergePolicy]; queryBlock(context); if ([context hasChanges]) { NSError*err; [context save:&amp;err]; if (err) { NSLog(@"context save: %@",[err localizedDescription]); } } }); } </code></pre> <p>and call it as :</p> <pre><code>CoreStorage* cs = [CoreStorage sharedInstance]; NSArray* list = [ws GetSections]; //array of NSDictionaries //if add this to operationQuiue resunt the same [cs query:^(NSManagedObjectContext *moc) { NSLog(@"START"); for (NSDictionary *section in list) { NSNumber* Id= @([[section objectForKey:@"section_id"] integerValue]); NSFetchRequest * fetchRequest = [NSFetchRequest new]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"Section" inManagedObjectContext: moc]; [fetchRequest setEntity:entity]; [fetchRequest setFetchLimit:1]; [fetchRequest setIncludesSubentities:NO]; [fetchRequest setPredicate: [NSPredicate predicateWithFormat:@"section_id=%@",Id]]; NSError *error =nil; Section *entry; if ([moc countForFetchRequest:fetchRequest error:&amp;error] &gt;0) { entry = [moc executeFetchRequest:fetchRequest error:nil][0]; NSLog(@"exist"); //this never call } else { entry = [NSEntityDescription insertNewObjectForEntityForName:@"Section" inManagedObjectContext:moc]; NSLog(@"NEW"); } entry.section_id = Id; entry.timeStamp = [NSDate date]; } }]; </code></pre> <p>Any sugastions please?</p>
 

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