Question

我正在使用三个不同的NSFetchedResultsController从我的sqlite数据库中获取数据记录。在设备（iOS 3.1.3）上测试时，其中一个给我带来了困难。在模拟器（iOS 4.2，deploymentTarget 3.1.3）中运行它可以正常工作。

在设备上，fetch返回的对象既不是NSDictionaries，也不是NSDictionaries，也不是故障。

以下是fetchedResultsController的定义：

- (NSFetchedResultsController *)fetchedResultsControllerForLocID
{
    if (_fetchedResultsControllerForLocID != nil) 
        return _fetchedResultsControllerForLocID;

    NSSortDescriptor *sortDescriptor_00 = [[NSSortDescriptor alloc] initWithKey: kLocationsDatabaseLocationIDKeyPath 
                                                                      ascending: TRUE];

    NSArray *sortDescriptors = [[NSArray alloc] initWithObjects: sortDescriptor_00, nil];

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

    NSEntityDescription *entity = [NSEntityDescription entityForName: kLocationsDatabaseAlternateNameEntityName
                                              inManagedObjectContext: self.managedObjectContext];
    [fetchRequest setEntity:entity];
    [fetchRequest setFetchBatchSize: 80];

    [fetchRequest setResultType: NSDictionaryResultType];
    [fetchRequest setPropertiesToFetch: [NSArray arrayWithObject: kLocationsDatabaseLocationIDKeyPath]];
    [fetchRequest setReturnsDistinctResults: TRUE];
    [fetchRequest setReturnsObjectsAsFaults: FALSE];
    [fetchRequest setSortDescriptors: sortDescriptors];

    NSFetchedResultsController *theFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest: fetchRequest 
                                managedObjectContext: self.managedObjectContext
                                  sectionNameKeyPath: nil
                                           cacheName: kLocationDatabaseAltNameLocIDRequestCacheName];

    self.fetchedResultsControllerForLocID = theFetchedResultsController;

    [fetchRequest release];
    [theFetchedResultsController release];

    [sortDescriptor_00 release];
    [sortDescriptors release];
    return _fetchedResultsControllerForLocID;
}

这是实际的获取：

- (void) searchLocationsDBWithFRCFor: (NSString *) locationName
{
    [NSFetchedResultsController deleteCacheWithName: kLocationDatabaseAltNameLocIDRequestCacheName];
    NSString *normLocationName = [self normalizeString: locationName];
    NSPredicate *searchPredicate = [NSPredicate predicateWithFormat:@"(%K >= %@) && (%K <= %@)", kLocationsDatabaseLocationSearchNameKeyPath, normLocationName, kLocationsDatabaseLocationSearchNameKeyPath, [self upperBoundSearchString: normLocationName]];

    [[self.fetchedResultsControllerForLocID fetchRequest] setPredicate: searchPredicate];

    NSError *error = nil;

    if (![self.fetchedResultsControllerForLocID performFetch:&error])
    {
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }

    NSMutableArray *tempArray = [[NSMutableArray alloc] init];

    //this line craches on the device:    
    for(NSDictionary* tempIDDict in [self.fetchedResultsControllerForLocID fetchedObjects])
    {
        [tempArray addObject: [tempIDDict objectForKey: kLocationsDatabaseLocationIDKeyPath]];
    }  

    searchPredicate = [NSPredicate predicateWithFormat:@"(%K IN %@)", kLocationsDatabaseLocationIDKeyPath, tempArray];
    [tempArray release];
    //some more fetching...
}

在模拟器中，我得到了这些SQL-Callbacks：

2011-01-22 20:31:33.660 App[24386:207] CoreData: sql: pragma cache_size=200
2011-01-22 20:31:33.661 App[24386:207] CoreData: sql: SELECT Z_VERSION, Z_UUID, Z_PLIST FROM Z_METADATA
2011-01-22 20:31:33.664 App[24386:207] CoreData: sql: SELECT DISTINCT t0.ZLOCATIONID FROM ZALTERNATENAME t0 WHERE ( t0.ZLOCATIONSEARCHNAME >= ? AND t0.ZLOCATIONSEARCHNAME <= ?) ORDER BY t0.ZLOCATIONID
2011-01-22 20:31:33.666 App[24386:207] CoreData: annotation: sql connection fetch time: 0.0015s
2011-01-22 20:31:33.666 App[24386:207] CoreData: annotation: total fetch execution time: 0.0024s for 6 rows.

然而，在设备上运行它，给我这个：

2011-01-22 20:39:07.318 App[241:207] CoreData: sql: pragma cache_size=1000
2011-01-22 20:39:07.324 App[241:207] CoreData: sql: SELECT Z_VERSION, Z_UUID, Z_PLIST FROM Z_METADATA
2011-01-22 20:39:07.348 App[241:207] CoreData: sql: SELECT 0, t0.Z_PK FROM ZALTERNATENAME t0 WHERE ( t0.ZLOCATIONSEARCHNAME >= ? AND t0.ZLOCATIONSEARCHNAME <= ?) ORDER BY t0.ZLOCATIONID
2011-01-22 20:39:07.386 App[241:207] CoreData: annotation: sql connection fetch time: 0.0374s
2011-01-22 20:39:07.388 App[241:207] CoreData: annotation: total fetch execution time: 0.0404s for 16 rows.
2011-01-22 20:39:07.400 App[241:207] CoreData: sql: SELECT DISTINCT t0.ZLOCATIONID FROM ZALTERNATENAME t0 WHERE t0.Z_PK IN (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?) ORDER BY t0.ZLOCATIONID LIMIT 80
2011-01-22 20:39:07.407 App[241:207] CoreData: annotation: sql connection fetch time: 0.0061s
2011-01-22 20:39:07.409 App[241:207] CoreData: annotation: total fetch execution time: 0.0085s for 6 rows.

也不错，如果没有出现错误：

2011-01-22 20:39:07.411 App[241:207] *** -[NSKnownKeysDictionary1 objectID]: unrecognized selector sent to instance 0x1e4f80
2011-01-22 20:39:07.414 App[241:207] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[NSKnownKeysDictionary1 objectID]: unrecognized selector sent to instance 0x1e4f80'
2011-01-22 20:39:07.417 App[241:207] Stack: (
861696817,
860329709,
861700631,
861203093,
861166272,
832412333,
832413791,
77245,
66451,
66643,
845720837,
861449139,
861447005,
861059891,
861060063,
834770799,
834765939,
12391,
12316
)
terminate called after throwing an instance of 'NSException'
Program received signal: “SIGABRT”.

为什么Core Data会在设备上运行时改变查询？

NSKnownKeysDictionary1究竟是什么？为什么尝试访问控制器的fetchedObjects会在设备上出现错误？

有什么想法吗？提前谢谢！

Answer 1

删除以下行，看看是否能解决问题。 [fetchRequest setFetchBatchSize：80];

我有一个类似的问题，我的应用程序运行良好，但在使用SDK 4.2构建的iOS 3.x设备上崩溃。我在这里找到了解决方案： setFetchLimit and sectionNameKeyPath on iPhone OS4 (XCode 3.2.3) cause crash

FetchedResultsController返回未知对象

1 个答案: