核心数据应用程序崩溃"controllerWillChangeContent:无法识别的选择器发送到实例"

Question

我有一个包含2个视图的核心数据应用程序.第一个视图列出"房间",第二个视图列出房间中的"场景"."房间"页面有一个编辑NavItem按钮,按下该按钮可启用添加NavItem按钮.您可以从此处删除和添加房间.添加的房间只是在表格中显示默认的"新房间"名称.第二个视图是所选房间中的场景列表.同样在这里,您可以删除和添加场景,添加的场景只会出现在名为"新场景"的表格中.没什么特别的.

我FetchedResultsController在两个视图控制器中都使用了一个,其中一个场景NSPredicate只能返回所选房间的场景.我还使用了controllerWillChangeContent,controllerDidChangeContent等,为表视图更新委托方法.

这一切都很好,但通常在房间和场景周围导航然后尝试删除一个场景它会崩溃.如果你玩的时间足够长,它将不可避免地崩溃.它只在删除场景时发生.如果您按下编辑按钮并删除一个场景并且它可以正常工作,则该编辑会话中的所有以下删除操作将始终有效.它只会在第一次删除编辑会话时崩溃.

我得到的错误很奇怪:

由于未捕获的异常'NSInvalidArgumentException'终止应用程序,原因:' - [__ NSCFType controllerWillChangeContent:]:无法识别的选择器发送到实例0x5e02d70'

此错误的第一部分有时会发生变化.有时它是__NSCFType,有时它是CALayer.仅在删除场景时才会出现此错误.添加场景很好100%.

我已经阅读了另一篇关于stackoverflow的文章,该文章表明这​​些错误可能来自内存管理问题.我已经仔细检查了代码,并通过仪器与泄漏仪器一起运行.没有泄漏.

还有什么我可以检查的吗？有任何想法吗？

这是相关的代码..

来自ScenesTableViewController.m:

// used to show/hide the add button

- (void)setEditing:(BOOL)editing animated:(BOOL)animate
{
    [super setEditing:editing animated:animate];
    if(editing)
    {
        self.navigationItem.leftBarButtonItem = addButton;
    }
    else
    {
        self.navigationItem.leftBarButtonItem = nil;
    }
}

// called when the add button is pressed

- (void)addAction {
    NSEntityDescription *myContentEntity = [NSEntityDescription entityForName:@"Scene" inManagedObjectContext:managedObjectContext];
    Scene *contentToSave = [[Scene alloc] initWithEntity:myContentEntity insertIntoManagedObjectContext:managedObjectContext];
    [contentToSave setValue:@"New Scene" forKey:@"Name"];
    [parentRoom addRoomToScenesObject:contentToSave];

    NSError *error;
    if (![managedObjectContext save:&error]) {
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        exit(-1);
    }
    [contentToSave release];
}

// delegate method that's being sent unrecognised selectors

- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller {
    // The fetch controller is about to start sending change notifications, so prepare the table view for updates.
    [self.tableView beginUpdates];
}

// cell display code

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = nil; 
    cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier]; 
    if (!cell) {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle
                                       reuseIdentifier:CellIdentifier] autorelease]; 
        [cell setAccessoryType:UITableViewCellAccessoryDisclosureIndicator];
    }
    [self configureCell:cell atIndexPath:indexPath]; 
    return cell;
}

- (void)configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath {
    NSManagedObject *mo = nil;
    NSString *temp = nil;
    mo = [fetchedResultsController objectAtIndexPath:indexPath];
    temp = [mo valueForKey:@"Name"];
    [[cell textLabel] setText:temp];
}

// cell editing code

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath {

    if (editingStyle == UITableViewCellEditingStyleDelete) {
        // Delete the managed object at the given index path.
        [managedObjectContext deleteObject:[fetchedResultsController objectAtIndexPath:indexPath]];

        NSError *error;
        if (![managedObjectContext save:&error]) {
            // Update to handle the error appropriately.
            NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
            exit(-1);  // Fail
        }
    }   
    else if (editingStyle == UITableViewCellEditingStyleInsert) {
        // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
    }    
}

// NSFetchedResultsController code

- (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:@"Scene" inManagedObjectContext:managedObjectContext];
    NSSortDescriptor *nameDescriptor = [[NSSortDescriptor alloc] initWithKey:@"Name" ascending:YES];
    NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:nameDescriptor, nil];
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(SceneToRoom == %@)", parentRoom];

    [fetchRequest setSortDescriptors:sortDescriptors];   
    [fetchRequest setPredicate:predicate];
    [fetchRequest setEntity:entity];

    // 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:managedObjectContext sectionNameKeyPath:nil cacheName:nil];
    aFetchedResultsController.delegate = self;
    self.fetchedResultsController = aFetchedResultsController;

    [aFetchedResultsController release];
    [fetchRequest release];    
    [nameDescriptor release];
    [sortDescriptors release];

    return fetchedResultsController;
} 

Answer 1

该错误很可能来自NSFetchedResultsController具有已释放代理的错误.你有一个UIViewController你发布的并且没有发布关联的NSFetchedResultsController吗？