Question

我有这个fetchedResult方法：

- (NSFetchedResultsController *)fetchedResultsController
{
    if (__fetchedResultsController != nil) {
        return __fetchedResultsController;
    }

    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];

    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Cards" inManagedObjectContext:self.managedObjectContext];
    [fetchRequest setEntity:entity];

    [fetchRequest setFetchBatchSize:20];

    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"Cards" ascending:YES];
    NSArray *sortDescriptors = [NSArray arrayWithObjects:sortDescriptor, nil];
    [fetchRequest setSortDescriptors:sortDescriptors];

    NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:@"Master"];
    aFetchedResultsController.delegate = self;
    self.fetchedResultsController = aFetchedResultsController;

    NSError *error = nil;

    if (![self.fetchedResultsController 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 __fetchedResultsController;
}

但是当我要求self.fetchedResultsController.fetchedObjects.count时，它总会给我一件物品，而不是它应该给我的物品。第一项是这个："<Cards: 0x83e9c50> (entity: Cards; id: 0x83e9c80 <x-coredata:///Cards/t8C371600-7875-468C-A529-C918F0008C384> ; data: {\n cardID = nil;\n favourite = 0;\n imageData = nil;\n})"但是通过终端检查sqlite我可以看到这个项目不在那里。什么可能是什么？

Answer 1

很难理解发生了什么。你的代码看起来不错。但是如果你使用缓存机制，这可能是你的奇怪行为。

要进行测试，请尝试在nil中使用NSFetchedResultsController而不是缓存，或先删除缓存，然后再执行请求。

+ (void)deleteCacheWithName:(NSString *)name

如果您通过nil，则会删除所有奖金。

如果你解决了，请告诉我。

P.S。我认为在引擎盖下，现金可以保存，并且可以在不同的应用创业公司之间生活。有谁知道这个？

CoreData NSFetchedResultsController计数无法正常工作

1 个答案: