Question

我是Objective-c编程的新手。我正在尝试制作我的第一个应用程序，但我无法解决一个问题。

我在我的应用程序中使用UICollectionView和NSFetchedResultController。该应用程序从Web下载数据，并使用NSOperationQueue异步执行此操作。当我在模拟器中测试我的应用程序时，一切正常，但是当我在iPad 3上测试它时，我经常遇到这个错误。

* 断言失败 - [UICollectionView _endItemAnimations]，/ SourceCache / UIKit / UIKit-2380.17 / UICollectionView.m：2801

* 由于未捕获的异常'NSInternalInconsistencyException'而终止应用程序，原因：'无效更新：第0部分中的项目数无效。更新后现有部分中包含的项目数（28）必须等于更新前该部分中包含的项目数（26），加上或减去从该部分插入或删除的项目数（插入1个，删除0个），加上或减去移入的项目数或超出该部分（0移入，0移出）。'

我不知道为什么因为我将maxConcurrentOperationCount设置为1而且我认为在这种情况下所有操作导致将项目按顺序插入到UICollectionView中......可能出错了什么以及我应该更改什么？

mateusz

如果有人仍然对我的代码感兴趣：

当我的NSOperation结束时，我正在调用此方法：

- (void)collectionViewUpdaterDidFinish:(CollectionViewUpdater *)updater {
    [Artwork  artworkWithBehanceInfo:self.projectsData
                        andImageData:updater.imageData
                             atIndex:updater.projectIndex
                  forIndexInDataBase:updater.indexPathInCollectionView.item withDataHelper:self.dataHelper];


    NSIndexPath *indexPath = updater.indexPathInCollectionView;
    [self.dataHelper fetchData];
    [self.myCollectionView insertItemsAtIndexPaths:@[indexPath]];
    [self.pendingOperations.downloadsInProgress removeObjectForKey:indexPath];
    if ([self.dataHelper.fetchedResultsController.fetchedObjects count]==self.numberOfLastItemOnPage){
        [self.refresh endRefreshing];
        [self stopAnimation];
        self.progressView.hidden = YES;
        [[UIApplication sharedApplication] setNetworkActivityIndicatorVisible:NO];

    }
}


- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{

    static NSString *CellIdentifier = @"ResultCell";
    ResultCellView *cell = [collectionView dequeueReusableCellWithReuseIdentifier:CellIdentifier forIndexPath:indexPath];

    Artwork *artwork = [self.dataHelper.fetchedResultsController objectAtIndexPath:indexPath];
    cell.title.text = [artwork.title stringByAppendingString:@"\n "];
    cell.owner.text = [NSString stringWithFormat:@"%@",artwork.owner];
    cell.fields.text = artwork.fields;
    cell.numberOfViews.text = [NSString stringWithFormat:@"%@",artwork.views];
    cell.numberOfLikes.text = [NSString stringWithFormat:@"%@",artwork.likes];
    cell.numberOfComments.text = [NSString stringWithFormat:@"%@",artwork.comments];
    cell.publishedDate.text = artwork.publishedDate;
    if ([artwork.hasThumbnail boolValue]) {
        dispatch_queue_t downloadQueue = dispatch_queue_create("imagecache", NULL);
        dispatch_async(downloadQueue, ^{
            UIImage *productImage = [UIImage imageWithData:artwork.thumbnail];
            CGSize imageSize = productImage.size;
            UIGraphicsBeginImageContext(imageSize);
            [productImage drawInRect:CGRectMake(0, 0, imageSize.width, imageSize.height)];
            productImage = UIGraphicsGetImageFromCurrentImageContext();
            UIGraphicsEndImageContext();
            dispatch_async(dispatch_get_main_queue(), ^ {
                cell.thumbnailImage.image = productImage;
                cell.thumbnailImage.hidden = NO;
            });
        });


    }
    else {
        NSLog(@"Has to download thumbnail");
        cell.thumbnailImage.hidden = YES;
        [self startOperationsForPhotoRecord:artwork atIndexPath:indexPath];

    }

    if ([self.dataHelper.fetchedResultsController.fetchedObjects count]==self.numberOfLastItemOnPage) {
        self.cellRefreshed = YES;
    }

   // it must be redifined for collections in behance!


    if (indexPath.item >=(self.numberOfLastItemOnPage-10) &&self.cellRefreshed &&([self.projectsData count]%12==0)) {

        self.numberOfFirstItemOnPage = self.numberOfLastItemOnPage+1;
        self.numberOfLastItemOnPage +=12;
        [self downloadMoreProjects];
        self.cellRefreshed = NO;
    }

    cell.selectedBackgroundView = [[UIView alloc] initWithFrame:CGRectZero];
    cell.selectedBackgroundView.backgroundColor = [[UIColor blackColor] colorWithAlphaComponent:0.5f];



    return cell;
}

断言失败 - [UICollectionView _endItemAnimations]

0 个答案: