Question

我对NSFetchedResultsCOntroller有一个很大的问题。我正在使用fetchedResultsContrioller，我有3个标签的界面。他们也使用核心数据。但我只有一个问题。

Faktura *faktura = [self.fetchedResultsController objectAtIndexPath:indexPath];

cell.textLabel.text = faktura.NumerFV; // THE CRASH IS HERE

int productsCount = [faktura.Produkty count]; // OR HERE
NSString *kontrahentName = [faktura.Kontrahent valueForKey:@"NazwaKrotka"]; // OR HERE

cell.detailTextLabel.text = [NSString stringWithFormat:@"nabywca: %@, produktów: %d",kontrahentName, productsCount];

cell.imageView.image = [UIImage imageNamed:@"faktura_cell_image.png"];
cell.hidesImageWhileEditing = YES;
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;

Faktura是我的NSManagedObject子类。

NSZombie说： -[CFDictionary retain]: message sent to deallocated instance 0x5d619d0

我的fetchedResultsController实现：

- (NSFetchedResultsController *)fetchedResultsController {

if (__fetchedResultsController != nil) return __fetchedResultsController;

// Setup the table

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

// Setup the sort descriptors

NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"DataWystawienia" ascending:YES];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
[fetchRequest setSortDescriptors:sortDescriptors];

// Create the fetched results controller

NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:nil];
aFetchedResultsController.delegate = self;
self.fetchedResultsController = aFetchedResultsController;

[aFetchedResultsController release];
[fetchRequest release];
[sortDescriptor release];
[sortDescriptors release];

NSError *error = nil;
if (![self.fetchedResultsController performFetch:&error]) { // THE CRASH IS HERE UNLESS I INIT NSFetchedResultsController WITH cacheName:nil. (IF IT'LL BE cacheName:@"Root" IT CRASHES.)

    UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"Błąd Krytyczny" message:@"Wystąpił nieznany błąd przy zmienianiu zawartości w bazie danych. Dla dobra twoich danych prosimy niezwłocznie wyjść z aplikacji i spróbować ponownie." delegate:self cancelButtonTitle:@"OK" otherButtonTitles:nil];
    [alert show];
    [alert release];

    NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
    abort();
}

return __fetchedResultsController;
}

Faktura.h

#import <Foundation/Foundation.h>
#import <CoreData/CoreData.h>

@interface NSArrayToDataTransformer : NSValueTransformer @end
@interface NSDictionaryToDataTransformer : NSValueTransformer @end

@interface Faktura : NSManagedObject

@property (nonatomic, retain) NSDate * DataZaplaty;
@property (nonatomic, retain) NSString * NumerFV;
@property (nonatomic, retain) NSDate * DataWystawienia;
@property (nonatomic, retain) NSDate * DataSprzedazy;
@property (nonatomic, retain) id Produkty;
@property (nonatomic, retain) id Kontrahent;

@end

Faktura.m

#import "Faktura.h"

@implementation Faktura

@dynamic DataZaplaty;
@dynamic NumerFV;
@dynamic DataWystawienia;
@dynamic DataSprzedazy;
@dynamic Produkty;
@dynamic Kontrahent;

+ (void)initialize {
if (self == [Faktura class] ) {
    NSArrayToDataTransformer *arrayTransformer = [[NSArrayToDataTransformer alloc] init];
    [NSValueTransformer setValueTransformer:arrayTransformer forName:@"NSArrayToDataTransformer"];
    NSDictionaryToDataTransformer *dictTransformer = [[NSDictionaryToDataTransformer alloc] init];
    [NSValueTransformer setValueTransformer:dictTransformer forName:@"NSDictionaryToDataTransformer"];
}
}

@end


@implementation NSArrayToDataTransformer

+ (BOOL)allowsReverseTransformation {
return YES;
}

+ (Class)transformedValueClass {
return [NSData class];
}


- (id)transformedValue:(id)value {
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:value];
return data;
}


- (id)reverseTransformedValue:(id)value {
NSArray *array = [NSKeyedUnarchiver unarchiveObjectWithData:value];
return [array autorelease];
}

@end


@implementation NSDictionaryToDataTransformer

+ (BOOL)allowsReverseTransformation {
return YES;
}

+ (Class)transformedValueClass {
return [NSData class];
}


- (id)transformedValue:(id)value {
NSData *data = [NSKeyedArchiver archivedDataWithRootObject:value];
return data;
}


- (id)reverseTransformedValue:(id)value {
NSDictionary *dict = [NSKeyedUnarchiver unarchiveObjectWithData:value];
return [dict autorelease];
}

@end

我的Faktura对象插入代码

- (void)fakturaCreator:(FakturaCreator *)form didEndWithValues:(NSDictionary *)values {

    NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
    NSEntityDescription *entity = [[self.fetchedResultsController fetchRequest] entity];
    Faktura *newFaktura = [NSEntityDescription insertNewObjectForEntityForName:[entity name] inManagedObjectContext:context];

    [newFaktura setNumerFV:[values valueForKey:@"id"]];
    [newFaktura setDataWystawienia:[values valueForKey:@"creationDate"]];
    [newFaktura setDataSprzedazy:[values valueForKey:@"sellDate"]];
    [newFaktura setDataZaplaty:[values valueForKey:@"paymentDate"]];
    [newFaktura setKontrahent:[values valueForKey:@"kontrahent"]];
    [newFaktura setProdukty:[values valueForKey:@"produkty"]];

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

    [self.emptySectionView setHidden:YES];
}

FakturaCreator是我的UIViewController，用户在其中创建发票。值数组包含值字典：我的发票号（NSString），各种日期（NSDate），客户端（NSDictionary）和产品（NSArray）。

请帮帮我！如果你想要一些额外的代码，我会把它放在这里。

编辑： definetly objectAtIndexPath:错误。当我评论所有单元格设置代码（它将显示空单元格）然后尝试删除单元格时，应用程序在包含objectatIndexPath:的行崩溃。

编辑＃2：有人吗？请帮助我...... :(

Answer 1

我想我看到了问题。在NSArrayToDataTransformer中，您有：

- (id)reverseTransformedValue:(id)value {
    NSArray *array = [NSKeyedUnarchiver unarchiveObjectWithData:value];
    return [array autorelease];
}

由于unarchiveObjectWithData:不以“alloc”，“new”，“copy”或“mutableCopy”开头，因此您不拥有该对象，因此可能无法自动释放它。您的NSDictionaryToDataTransformer中存在同样的问题。

Answer 2

您将值变换器包含在类中并且使用+initialize是非标准的。尽管+initialize应该有效，但建议在Core Data文档中不要使用任何类型的初始化方法，而是依赖awakeFromFetch进行初始化。

我会检查你的tableview方法，例如numberOfRowsInSection:，以确保从tableview中获取正确的索引。如果tableview中的行和fetchedObjects数组的计数不同步，则可能会发生此类崩溃。

NSFetchedResultsController objectAtIndexPath崩溃（EXC_BAD_ACCESS）

2 个答案: