Question

我正在使用cocos2d开发一个应用程序，该应用程序获取给定用户的所有Facebook照片，然后在CollectionView中填充它们。我通过图表查询获取所有照片URL's并将它们插入数组列表中。

[request startWithCompletionHandler:^(FBRequestConnection *connection,
                                          id result,
                                          NSError *error){
        NSArray *resultData = [result objectForKey:@"data"];

        for (int i=0; i<100;i++) {
            NSString *sourceURL = [[resultData objectAtIndex:0] objectForKey:@"source"];
            [_imagesUrlList addObject:sourceURL];
        }

        UICollectionViewFlowLayout *collectionFlowLayout = [[UICollectionViewFlowLayout alloc]init];
        [collectionFlowLayout setSectionInset:UIEdgeInsetsMake(5, 7, 5, 7)];
        _collectionView = [[UICollectionView alloc]initWithFrame:CGRectMake(_masterView.frame.origin.x, _masterView.frame.origin.y+TOP_MARGIN, _masterView.frame.size.width, _masterView.frame.size.height-TOP_MARGIN) collectionViewLayout:collectionFlowLayout];
        [collectionFlowLayout release];
        _collectionView.delegate = self;
        _collectionView.dataSource = self;
        [_collectionView registerClass:[ImageCell class] forCellWithReuseIdentifier:@"cellIdentifier"];
        [_collectionView setBackgroundColor:[UIColor colorWithRed:226.f/255.f green:228.f/255.f blue:221.f/255.f alpha:1]];
        [_masterView addSubview:_collectionView];
        [[LoadingView sharedLoadingView] stopTheLoadingActivityView];
        [[LoadingView sharedLoadingView] moveVertically:-30];

        [self loadImagesInView];
    }];

为了测试大量照片，我在图片网址0处插入了100倍。之后，使用Facebook请求中的给定URL将图像加载到单独的线程上，因为NSURLConnection会根据请求阻止该线程。

    -(void)loadImagesInView{
    dispatch_async( dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
    for (int i=0; i<[_imagesUrlList count]; i++) {
        if (_backed) {
            return;
        }
        NSLog(@"out");
        NSString *sourceURL = [_imagesUrlList objectAtIndex:i];
        NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:sourceURL]];
        NSLog(@"conn %d",i);
        dispatch_async( dispatch_get_main_queue(), ^{
            UIImage *image = [UIImage imageWithData:data];
                image = [self imageWithImage:image scaledToSize:CGSizeMake(100, 100)];

                [_imageViewsList addObject:image];


                [_collectionView reloadData];




                NSLog(@"finish %d",i);

            });



    }
        });
}

问题是我在视图中加载图像时无法选择图片。在方法完成之前，甚至不会调用didSelect方法。可能是因为当图像准备插入时我调用了reloadData。您可以在下面看到选择，删除和填充集合视图的方法。

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

    static NSString *cellIdentifier = @"cellIdentifier";

    ImageCell *cell= (ImageCell*)[collectionView dequeueReusableCellWithReuseIdentifier:cellIdentifier forIndexPath:indexPath];
    UIImage *photoImg = [_imageViewsList objectAtIndex:indexPath.row];
    [cell.imageView setImage:photoImg];
    NSNumber *rowNsNum = [NSNumber numberWithUnsignedInt:indexPath.row];
    if ([_selectedCells containsObject:[NSString stringWithFormat:@"%@",rowNsNum]]) {
        [cell.layer setBorderColor:[[UIColor colorWithRed:255.f/255.f green:255.f/255.f blue:255.f/255.f alpha:0.5] CGColor]];
    }
    else {
        [cell.layer setBorderColor:[[UIColor colorWithRed:0.f/255.f green:0.f/255.f blue:0.f/255.f alpha:0.5] CGColor]];
    }
    return cell;
}
-(void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{
    ImageCell *imgCell = (ImageCell*)[_collectionView cellForItemAtIndexPath:indexPath];
    if ([_selectedCells containsObject:[NSString stringWithFormat:@"%d",[indexPath row]]]) {
        [_selectedCells removeObject:[NSString stringWithFormat:@"%d",[indexPath row]]];
        [imgCell.layer setBorderColor:[[UIColor colorWithRed:0.f/255.f green:0.f/255.f blue:0.f/255.f alpha:0.5] CGColor]];
    }
    else {
        [_selectedCells addObject:[NSString stringWithFormat:@"%d",[indexPath row]]];
        [imgCell.layer setBorderColor:[[UIColor colorWithRed:255.f/255.f green:255.f/255.f blue:255.f/255.f alpha:0.5] CGColor]];
    }
}
-(void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(NSIndexPath *)indexPath{
    ImageCell *imgCell = (ImageCell*)[_collectionView cellForItemAtIndexPath:indexPath];
    if ([_selectedCells containsObject:[NSString stringWithFormat:@"%d",[indexPath row]]]) {
        [_selectedCells removeObject:[NSString stringWithFormat:@"%d",[indexPath row]]];
        [imgCell.layer setBorderColor:[[UIColor colorWithRed:0.f/255.f green:0.f/255.f blue:0.f/255.f alpha:0.5] CGColor]];
    }
}

Answer 1

放置[_collectionView reloadData];在旁边的for循环..

 -(void)loadImagesInView{
dispatch_async( dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
for (int i=0; i<[_imagesUrlList count]; i++) {
    if (_backed) {
        return;
    }
    NSLog(@"out");
    NSString *sourceURL = [_imagesUrlList objectAtIndex:i];
    NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:sourceURL]];
    NSLog(@"conn %d",i);
    dispatch_async( dispatch_get_main_queue(), ^{
        UIImage *image = [UIImage imageWithData:data];
            image = [self imageWithImage:image scaledToSize:CGSizeMake(100, 100)];

            [_imageViewsList addObject:image];


            NSLog(@"finish %d",i);

        });

}
[_collectionView reloadData];
    });

}

在填充时从集合视图中选择一个单元格

1 个答案: