如何以编程方式填充核心数据存储？

Question

编辑:可以从crashTest下载展示崩溃的最小项目.它是通过在XCode中选择"基于核心数据的导航"项目模板并修改可能的十行来创建的.

当一次添加一个部分和两个对象时,我已经没有毛发拉动了.

崩溃发生在调用内部例程的末尾[managedObjectContext save:&error].

崩溃是一个超出范围的异常NSArray:

Serious application error.  Exception was caught during Core Data change processing: *** -[NSCFArray objectAtIndex:]: index (1) beyond bounds (1) with userInfo (null)

也许相关,当异常发生时,我的获取结果控制器controllerDidChangeContent:委托例程在调用堆栈中.它只是调用我的表视图endUpdate例程.

我现在已经没想完了.我应该如何使用部分使用表格视图向核心数据存储中插入多个项目？

这是调用堆栈:

#0  0x901ca4e6 in objc_exception_throw
#1  0x01d86c3b in +[NSException raise:format:arguments:]
#2  0x01d86b9a in +[NSException raise:format:]
#3  0x00072cb9 in _NSArrayRaiseBoundException
#4  0x00010217 in -[NSCFArray objectAtIndex:]
#5  0x002eaaa7 in -[UITableView(_UITableViewPrivate) _endCellAnimationsWithContext:]
#6  0x002def02 in -[UITableView endUpdates]
#7  0x00004863 in -[AirportViewController controllerDidChangeContent:] at AirportViewController.m:463
#8  0x01c43be1 in -[NSFetchedResultsController(PrivateMethods) _managedObjectContextDidChange:]
#9  0x0001462a in _nsnote_callback
#10 0x01d31005 in _CFXNotificationPostNotification
#11 0x00011ee0 in -[NSNotificationCenter postNotificationName:object:userInfo:]
#12 0x01ba417d in -[NSManagedObjectContext(_NSInternalNotificationHandling) _postObjectsDidChangeNotificationWithUserInfo:]
#13 0x01c03763 in -[NSManagedObjectContext(_NSInternalChangeProcessing) _createAndPostChangeNotification:withDeletions:withUpdates:withRefreshes:]
#14 0x01b885ea in -[NSManagedObjectContext(_NSInternalChangeProcessing) _processRecentChanges:]
#15 0x01bbe728 in -[NSManagedObjectContext save:]
#16 0x000039ea in -[AirportViewController populateAirports] at AirportViewController.m:112

这是例程的代码.我道歉,因为许多行可能无关紧要,但我宁愿错误.当它调用时发生崩溃[context save:&error]:

- (void) insertObjects
{
NSManagedObjectContext *context = [fetchedResultsController managedObjectContext];
NSEntityDescription *entity = [[fetchedResultsController fetchRequest] entity];

NSManagedObject *newManagedObject = [NSEntityDescription insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context];

// If appropriate, configure the new managed object.
[newManagedObject setValue:@"new airport1" forKey:@"name"];
[newManagedObject setValue:@"???" forKey:@"code"];
[newManagedObject setValue:@"new country" forKey:@"country_name"];

newManagedObject = [NSEntityDescription insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context];
[newManagedObject setValue:@"new airport2" forKey:@"name"];
[newManagedObject setValue:@"???" forKey:@"code"];
[newManagedObject setValue:@"new country" forKey:@"country_name"];


// Save the context.
NSError *error = nil;
if (![context save:&error]) {
    NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
    abort();
}
}

注意:这些部分是country_name.此外,这四个NSFetchedResultsControllerDelegate例程是由XCode记录和预设的:

- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller {
[self.tableView beginUpdates];
}


- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
       atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type
{
switch(type) {
    case NSFetchedResultsChangeInsert:
        [self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex] withRowAnimation:UITableViewRowAnimationFade];
        break;
// other cases omitted because not occurring in this crash            

}
}


- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject
   atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type
  newIndexPath:(NSIndexPath *)newIndexPath
{
UITableView *tableView = self.tableView;

switch(type) {

    case NSFetchedResultsChangeInsert:
        [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
        break;
// other cases omitted because not occurring in this crash            
}
}


- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
[self.tableView endUpdates];
}

Answer 1

在我看来，这是 Cocoa Touch 中的一个错误。当然我可能是错的。无论如何，我找到了解决方法。

解决方法包括在四个委托例程中不执行任何操作，但仅限于这种情况。我最终添加了一个BOOL massUpdateiVar，在添加对象之前将其设置为 true，并在调用保存后将其重置为 false。

在四个委托例程中，我测试了massUpdate iVar。如果这是真的，我什么也不做，除了第四个，我重新加载整个表视图。

我得到：

- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller {
if (massUpdate)
    return;
[self.tableView beginUpdates];
}


- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
       atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type
{
if (massUpdate)
    return;
    <snip normal implementation>
}


- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject
   atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type
  newIndexPath:(NSIndexPath *)newIndexPath
{
if (massUpdate)
    return;
    <snip normal implementation>
}


- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
if (massUpdate)
    [self.tableView reloadData];
else
    [self.tableView endUpdates];
}