基于控件的表视图在实体的第二次插入时总是失败

我正在使用nsfetchedresultsController管理在具有一个部分的表视图中显示提取的托管对象。表以空开头,用户可以使用UI向其添加新实体。事实上,程序总是在添加第一个实体时工作,而在添加第二个实体时总是崩溃。有时碰撞时不会出现错误,其他时候会出现不同类型的错误(有些错误包括在下面)。通过日志语句和跟踪,我看到程序在nsfetchResultsController的委托的ControllerWillChangeContent(调用[self.tableView beginUpdates])方法退出后崩溃,但在调用代码中的任何其他方法之前。 以下是我的代码的一些相关部分。配置nsfetchedresultsController:

NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
[fetchRequest setEntity:[NSEntityDescription entityForName:@"Beer"
                                    inManagedObjectContext:self.managedObjectContext]];

// Configure request's entity and predicate
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES];
NSArray *sortDescriptors = [NSArray arrayWithObjects:sortDescriptor, nil];
[fetchRequest setSortDescriptors:sortDescriptors];
[sortDescriptor release];
[sortDescriptors release];

NSString *expression = [NSString stringWithFormat:@"brewery.name LIKE \"%@\"", self.brewery.name];
NSPredicate *predicate = [NSPredicate predicateWithFormat:expression];
[fetchRequest setPredicate:predicate];
self.resultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest
                                                             managedObjectContext:self.managedObjectContext
                                                               sectionNameKeyPath:nil
                                                                        cacheName:nil];
self.resultsController.delegate = self;
[fetchRequest release];

NSError *error = nil;
BOOL success = [resultsController performFetch:&error];
if (!success) {
    NSLog(@"Error fetching request %@", [error localizedDescription]);
}

添加新实体:

NSEntityDescription *entity = [NSEntityDescription entityForName:@"Beer" inManagedObjectContext:self.managedObjectContext];
Beer *beer = [[Beer alloc] initWithEntity:entity insertIntoManagedObjectContext:self.managedObjectContext];
beer.name = beerName;
beer.brewery = self.brewery;

我已经在文档中看到了关于在一个部分中显示表时出现问题的警告,并且我使用了苹果的解决方法来解决这个问题。无论如何,这些方法在崩溃之前不会被调用。

我收到的一些错误:

Serious application error.  Exception was caught during Core Data change processing: *** -[NSCFString compareObject:toObject:]: unrecognized selector sent to instance 0x4e808c0 with userInfo (null)
Serious application error.  Exception was caught during Core Data change processing: *** -[CALayer compareObject:toObject:]: unrecognized selector sent to instance 0x4e53b80 with userInfo (null)
Serious application error.  Exception was caught during Core Data change processing: *** -[UITextTapRecognizer controllerWillChangeContent:]: unrecognized selector sent to instance 0x4ca5d70 with userInfo (null)
Serious application error.  Exception was caught during Core Data change processing: *** -[CALayer controllerWillChangeContent:]: unrecognized selector sent to instance 0x4e271a0 with userInfo (null)
Serious application error.  Exception was caught during Core Data change processing: *** -[NSCFNumber countByEnumeratingWithState:objects:count:]: unrecognized selector sent to instance 0x4c96ee0 with userInfo (null)

正如您所看到的,错误(出现错误时)是不一致的,即使没有对代码进行任何更改。

有人知道我做错了什么吗?