奥基,我在这个核心数据站得较好,但我已想走一条路。 这就是我是如何在我心怀念的。 在我看来,主计长的工作量如下:

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

/*
 Set up the fetched results controller.
 */
// Create the fetch request for the entity.
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
// Edit the entity name as appropriate.
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Visit" 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:@"date" ascending:NO];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];

[fetchRequest setSortDescriptors:sortDescriptors];

// 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:@"Queue"];
aFetchedResultsController.delegate = self;
self.fetchedResultsController = aFetchedResultsController;

NSPredicate *predicate =[NSPredicate predicateWithFormat:@"(isActive == YES)"];
[fetchedResultsController.fetchRequest setPredicate:predicate];

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. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button.
     */
    NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
    abort();
}

return __fetchedResultsController;
}

这发挥了巨大作用。 我有我的表态,我有5个管理着正在显示的物体。 我正在讨论的问题是,我需要改变管理对象之一。

如您在前言中可以看到的那样,我只希望管理有<条码>的物体=YES。 我需要把有管理的物体的活性状态改变为NO,然后将其从左边的ResultsController, 并最终从表格中删除。

Here is how I am trying to do that:

-(void) seatedButton{
Visit * vis = [self.fetchedResultsController objectAtIndexPath:[NSIndexPath indexPathForRow:reloadIndex inSection:0]];

vis.isActive = [NSNumber numberWithBool:NO];

NSError *error = nil;

if (![self.managedObjectContext save:&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. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button.
     */
    NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
    abort();
}

[tableView reloadData];

}

看来,这将奏效,但它的确如此。 当表态重载时,有5个物体重新上载,符合基数的要求,只有4个。

What am I doing wrong here? What do I need to do to update the fetchedResultsController? Thanks!