objective-c - EXC_BAD_ACCESS:核心数据，NSFetchedResultsController和numberOfRowsInSection

在我的UITableViewController类中，我具有用于NSFetchResultsController的此getter函数

-(NSFetchedResultsController*) fetchedResultsController {

    if (_fetchedResultsController == nil) {
        FlipPadAppDelegate* app = (FlipPadAppDelegate*) [[UIApplication sharedApplication] delegate];
        NSFetchRequest* fetchRequest = [[NSFetchRequest alloc] init];
        [fetchRequest setEntity:
            [NSEntityDescription entityForName:@"FundClass" inManagedObjectContext:[app managedObjectContext]]];
        NSSortDescriptor* sortdesp = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES];
        [fetchRequest setSortDescriptors:[NSArray arrayWithObject:sortdesp]];

        [fetchRequest setFetchBatchSize:20];

        _fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest
                                                                       managedObjectContext:[app managedObjectContext]
                                                                         sectionNameKeyPath:nil
                                                                                  cacheName:@"_Stock"];


        _fetchedResultsController.delegate = self;
        [fetchRequest release];
        [sortdesp release];

        NSError *error;
        if (![[self fetchedResultsController] performFetch:&error]) {
            // Handle error
            NSLog(@"Unresolved error %@, %@", error, [error userInfo]);

        }
    }

    return _fetchedResultsController;

}

不知何故，当应用运行到这一点时，

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    // Return the number of rows in the section.
    id <NSFetchedResultsSectionInfo> sectionInfo = [[[self fetchedResultsController] sections] objectAtIndex:section];
    NSLog(@"numberOfRowsInSection %@", [sectionInfo numberOfObjects]);
    return [sectionInfo numberOfObjects];

}

它会触发一个EXC_BAD_ACCESS

sqllite数据库中有两个记录。

为什么例外？是因为我将sectionNameKeyPath设置为nil吗？还是因为我没有将视图的dataSource设置为此控制器？

最佳答案

因为您正在记录对象@“ numberOfRowsInSection％@”，而numberOfObjects是一个int，所以：

@property (nonatomic, readonly) NSUInteger numberOfObjects

使用@“ numberOfRowsInSection％i”代替。