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POCore Data with UIDocument: RelationShips of new Objects somwhow broken after didEnterBackground and reopen
 

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  1. POCore Data with UIDocument: RelationShips of new Objects somwhow broken after didEnterBackground and reopen
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    <p>I changed my app from a single context with sqlite store managed in the app delegate to UIManagedDocument (Like default Xcode template with Core Data activated). Now I have some strange behavior when trying to fetch objects that has been created since the current app startup, after I closed(backgrounded) and reopened the app.</p> <p>There are 2 Entities: Folder and Item. Folder to Item is a to-many-relationship.</p> <p>The predicate of my fetchedResultsController to display the items in the current folder looks like that:</p> <pre><code>[fetchRequest setEntity:[NSEntityDescription entityForName:@"Item" inManagedObjectContext:self.context]]; [fetchRequest setPredicate:[NSPredicate predicateWithFormat:@"(folder == %@)", self.currentFolder]]; </code></pre> <p>This still works fine beside one situation: - I create a new folder, add some items to it - Then close (background) and reopen the app - Select this folder to be displayed in the TableView Then the fetch returns 0 results.</p> <p>As soon as I kill the app and reopen it, the items of the folder are displayed again (and the fetchRequests returns the correct number of items).</p> <p>I did some further testing inside the viewDidAppear with some manual fetchRequests without a fetchedResultsController. And I really don't understand how this can happen.</p> <p>Both fetchRequests are basically the same (and also identical to the fetchedResultController's one), but the first one doesn't have the predicate and then checks in a for loop whether the item's folder ist the viewController's currentFolder.</p> <p>From my understanding, this should result in the exact same behavior, but while the predicate fails after backgrounding, the fetching of all items + testing in the for loop works fine all time.</p> <pre><code>// Returns fetchResult.count = 0 for new created folders after backgrounding the app [fetchRequest1 setEntity:[NSEntityDescription entityForName:@"Item" inManagedObjectContext:self.context]]; [fetchRequest1 setPredicate:[NSPredicate predicateWithFormat:@"(folder == %@)", self.currentFolder]]; NSArray *fetchResult1 = [self.context executeFetchRequest:fetchRequest1 error:nil]; // This time get all items in the context withour predicate [fetchRequest2 setEntity:[NSEntityDescription entityForName:@"Item" inManagedObjectContext:self.context]]; [fetchRequest2 setPredicate:nil]; NSArray *fetchResult2 = [self.context executeFetchRequest:fetchRequest1 error:nil]; // Filter to get only the items in the current folder NSMutableArray *filteredFetchResults2 = [NSMutableArray mutableArrayWithCapacity:0]; for (Item *item in fetchResult2) { if (item.folder == self.currentFolder) [filteredFetchResults2 addObject:item]; } // filteredFetchResults2 holds the correct items even after backgrounding. Why?!? </code></pre> <p>How could that be?</p>
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    1. USThyraz
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    1. COWhat is self.context? How are you "saving" the document?
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      1. USJody Hagins
 

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