问题：

Question

首先，我的应用程序的粗略描述是特定组织的杂志库应用程序。

我有一个定制的UICollectionViewCell完成了故事板原型。在原型中有3个视图 - UIImageView ， UILabel ， UILabel 。
此外，在 collectionView:cellForItemAtIndexPath: 中，我创建了一个
的实例
- UIButton （操作：@selector（downloadButtonTapped :)）
和
- UIProgressView ，其 tag=indexPath.item 和 hidden=YES 。然后，我将UIProgressView添加到相同索引的数组 - self.progressViewArray ，与单元格的 indexPath.item 相同
每次点击特定单元格的“下载”按钮并调用 downloadButtonTapped: 时，我都会获得单元格和 发件人的superview的superview的，即单元格。然后我检查[self.progressViewArray[indexPath.item] tag] == indexPath.item。如果条件满足，则执行 [self.progressViewArray[indexPath.item] setHidden:NO] 。

我有22个对象的数据源，因此，我有22个单元格。到目前为止，一切都像我想要的那样。即使我在视图中滚动单元格（出列）并返回视图（再循环），UIProgressView仍然存在。

问题：

progressView也会重新出现在其他单元格中！例如。如果我点击单元格3的“下载”按钮，UIProgressView正确显示在该单元格中，单元格10和19也显示“重复”UIProgressView 。此问题也适用于其他单元格。例如。当我点击单元格20的“下载”时，我向上滚动，我看到单元格12和4的加载UIProgressViews也一样，就像那些杂志也被下载一样。

为什么我提到相同是因为我有一个setDownloadProgressBlock来更新UIProgressViews的进度以及单元格3,10和19的进度UIProgressViews正在一起进行。

我真的希望我能在这里找到一些帮助，因为我已经在这个问题上花了很多天的时间来绞尽脑汁。

P.S。编辑下面的调试尝试。

以下是涉及的方法：

的CollectionView：cellForItemAtIndexPath：

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *identifier = @"Cell";
    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];

    // * ========== Configure Cell ========== *
    // Initialisation of UIImageViews and UILabels here.
    // ...

    // CREATION OF CELL'S DOWNLOADBUTTON
    UIButton *downloadButton = [UIButton buttonWithType:UIButtonTypeRoundedRect];
    [downloadButton addTarget:self action:@selector(downloadButtonTapped:) forControlEvents:UIControlEventTouchUpInside];
    [downloadButton setFrame:CGRectMake(178, 197, 140, 44)];
    [downloadButton setTitle:[self setDownloadButtonTitleAtIndexPath:indexPath.item] forState:UIControlStateNormal];
    [downloadButton setTitle:@"Downloading..." forState:UIControlStateDisabled];
    [downloadButton setEnabled:YES];
    [downloadButton setUserInteractionEnabled:YES];
    [downloadButton setTag:indexPath.item];
    [cell.contentView addSubview:downloadButton];


    // CREATION OF CELL'S UIPROGRESSVIEW
    UIProgressView *progressView = [[UIProgressView alloc] initWithProgressViewStyle:UIProgressViewStyleDefault];
    [progressView setFrame:CGRectMake(20, 248, 150, 9)];
    [progressView setHidden:YES];
    [progressView setTag:indexPath.item];
    [self.progressViewArray addObject:progressView];

    // This chunk is to prevent creating new progress views when the cells are being recycled.
    if ([self.progressViewArray[indexPath.item] tag] != progressView.tag)
    {
        [self.progressViewArray replaceObjectAtIndex:indexPath.item withObject:progressView];
    }

    [cell.contentView addSubview:self.progressViewArray[indexPath.item]];
    // * ---------- Configure Cell ---------- *

    return  cell;
}

downloadButtonTapped：

- (IBAction)downloadButtonTapped:(id)sender
{
    // Get the indexPath of tapped row.
    UICollectionViewCell *cell = (UICollectionViewCell *)[[sender superview] superview];
    NSIndexPath *indexPath = [self.collectionView indexPathForCell:cell];

    // If file does not exist.
    if (![[NSFileManager defaultManager] fileExistsAtPath:filePath])
    {
        // SHOW THE CELL'S HIDDEN UIPROGRESSVIEW
        if ([self.progressViewArray[indexPath.item] tag] == indexPath.item)
        {
            [self.progressViewArray[indexPath.item] setHidden:NO];
        }


        // AFHTTPRequestionOperation code here...

        // Track download progress.
        [operation setDownloadProgressBlock:^(NSUInteger bytesRead, long long totalBytesRead, long long totalBytesExpectedToRead)
         {
             for (UIProgressView *progressView in self.progressViewArray)
             {
                 if (progressView.tag == indexPath.item)
                 {
                     [progressView setProgress:(float) totalBytesRead / totalBytesExpectedToRead];
                 }
             }
         }];

        // Post download codes etc ...

        [operation start];
    }
}

感谢您的时间。我很感激......

编辑：

作为另一个调试尝试，我在NSLog(@"%@ at indexPath #%d", self.progressViewArray[indexPath.item], indexPath.item);之前做了一个return cell;，只是为了确认只有被攻击的单元格的UIProgressView受到影响（ setHidden = NO ），实际上它是

我点按了单元格3的下载按钮，滚动到底部，然后返回到顶部集合，照常查看好像单元格10和19的progressViews也是活动的，这就是我记录的内容。如您所见，在下载处于活动状态时，日志显示只有单元格3的progressView（tag = 3）是（ setHidden = NO ）。单元格10和19仍然隐藏/不受影响。但我不明白为什么我在那里看到一个活跃的进展。

这是日志：

2013-08-17 10:59:33.179 SFCCA[22885:907] <UIProgressView: 0x1c5bca00; frame = (20 248; 150 9); hidden = YES; opaque = NO; layer = <CALayer: 0x1c5d1000>> at indexPath #0
2013-08-17 10:59:33.187 SFCCA[22885:907] <UIProgressView: 0x1c59c7c0; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 1; layer = <CALayer: 0x1c5bb310>> at indexPath #1
2013-08-17 10:59:33.193 SFCCA[22885:907] <UIProgressView: 0x1c5aa1f0; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 2; layer = <CALayer: 0x1c5aa270>> at indexPath #2
2013-08-17 10:59:33.201 SFCCA[22885:907] <UIProgressView: 0x1c5b9860; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 3; layer = <CALayer: 0x1c5b9a30>> at indexPath #3
2013-08-17 10:59:33.207 SFCCA[22885:907] <UIProgressView: 0x1c5aa670; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 4; layer = <CALayer: 0x1c5b8d60>> at indexPath #4
2013-08-17 10:59:33.214 SFCCA[22885:907] <UIProgressView: 0x1c5b51d0; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 5; layer = <CALayer: 0x1c5b5270>> at indexPath #5

// Here, I have tapped cell 3's "Download" button.
// Notice that at the bottom of the log, when I have scrolled off cell 3 and back, the log shows that the progressView (tag=3) in cell 3 is hidden=NO
2013-08-17 10:59:43.389 SFCCA[22885:907] {downloadButtonTapped} - File does not exist. Download then read PDF.
2013-08-17 10:59:43.929 SFCCA[22885:907] <UIProgressView: 0x1c5d5a10; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 6; layer = <CALayer: 0x1c5b4420>> at indexPath #6
2013-08-17 10:59:43.938 SFCCA[22885:907] <UIProgressView: 0x1c5cd8e0; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 7; layer = <CALayer: 0x1c5b68d0>> at indexPath #7
2013-08-17 10:59:44.216 SFCCA[22885:907] <UIProgressView: 0x1d8c3b90; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 8; layer = <CALayer: 0x1d8c3c30>> at indexPath #8
2013-08-17 10:59:44.223 SFCCA[22885:907] <UIProgressView: 0x1c5e08d0; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 9; layer = <CALayer: 0x1c5b9330>> at indexPath #9
2013-08-17 10:59:44.600 SFCCA[22885:907] <UIProgressView: 0x1d8c9aa0; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 10; layer = <CALayer: 0x1d8c9480>> at indexPath #10
2013-08-17 10:59:44.607 SFCCA[22885:907] <UIProgressView: 0x1d8cb590; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 11; layer = <CALayer: 0x1d8cb4b0>> at indexPath #11
2013-08-17 10:59:45.160 SFCCA[22885:907] <UIProgressView: 0x1d8b9e20; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 12; layer = <CALayer: 0x1d8a6140>> at indexPath #12
2013-08-17 10:59:45.171 SFCCA[22885:907] <UIProgressView: 0x1d8cc060; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 13; layer = <CALayer: 0x1d8ca870>> at indexPath #13
2013-08-17 10:59:45.813 SFCCA[22885:907] <UIProgressView: 0x1d88dc10; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 14; layer = <CALayer: 0x1d88dc90>> at indexPath #14
2013-08-17 10:59:45.822 SFCCA[22885:907] <UIProgressView: 0x1d8cc9e0; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 15; layer = <CALayer: 0x1d872110>> at indexPath #15
2013-08-17 10:59:46.154 SFCCA[22885:907] <UIProgressView: 0x1c5ed300; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 16; layer = <CALayer: 0x1c5ed280>> at indexPath #16
2013-08-17 10:59:46.162 SFCCA[22885:907] <UIProgressView: 0x1c5eeae0; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 17; layer = <CALayer: 0x1c5eea00>> at indexPath #17
2013-08-17 10:59:46.652 SFCCA[22885:907] <UIProgressView: 0x1c5ee0f0; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 18; layer = <CALayer: 0x1c5e35f0>> at indexPath #18
2013-08-17 10:59:46.660 SFCCA[22885:907] <UIProgressView: 0x1c5efc70; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 19; layer = <CALayer: 0x1c5ee320>> at indexPath #19
2013-08-17 10:59:46.903 SFCCA[22885:907] <UIProgressView: 0x1c5e8b30; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 20; layer = <CALayer: 0x1c5e4aa0>> at indexPath #20
2013-08-17 10:59:46.914 SFCCA[22885:907] <UIProgressView: 0x1c5e8fd0; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 21; layer = <CALayer: 0x1c5e7e50>> at indexPath #21
2013-08-17 10:59:48.583 SFCCA[22885:907] <UIProgressView: 0x1d88dc10; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 14; layer = <CALayer: 0x1d88dc90>> at indexPath #14
2013-08-17 10:59:48.590 SFCCA[22885:907] <UIProgressView: 0x1d8cc9e0; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 15; layer = <CALayer: 0x1d872110>> at indexPath #15
2013-08-17 10:59:49.118 SFCCA[22885:907] <UIProgressView: 0x1d8b9e20; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 12; layer = <CALayer: 0x1d8a6140>> at indexPath #12
2013-08-17 10:59:49.127 SFCCA[22885:907] <UIProgressView: 0x1d8cc060; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 13; layer = <CALayer: 0x1d8ca870>> at indexPath #13
2013-08-17 10:59:49.730 SFCCA[22885:907] <UIProgressView: 0x1d8c9aa0; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 10; layer = <CALayer: 0x1d8c9480>> at indexPath #10
2013-08-17 10:59:49.736 SFCCA[22885:907] <UIProgressView: 0x1d8cb590; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 11; layer = <CALayer: 0x1d8cb4b0>> at indexPath #11
2013-08-17 10:59:50.106 SFCCA[22885:907] <UIProgressView: 0x1d8c3b90; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 8; layer = <CALayer: 0x1d8c3c30>> at indexPath #8
2013-08-17 10:59:50.113 SFCCA[22885:907] <UIProgressView: 0x1c5e08d0; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 9; layer = <CALayer: 0x1c5b9330>> at indexPath #9
2013-08-17 10:59:50.643 SFCCA[22885:907] <UIProgressView: 0x1c5d5a10; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 6; layer = <CALayer: 0x1c5b4420>> at indexPath #6
2013-08-17 10:59:50.649 SFCCA[22885:907] <UIProgressView: 0x1c5cd8e0; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 7; layer = <CALayer: 0x1c5b68d0>> at indexPath #7
2013-08-17 10:59:50.967 SFCCA[22885:907] <UIProgressView: 0x1c5aa670; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 4; layer = <CALayer: 0x1c5b8d60>> at indexPath #4
2013-08-17 10:59:50.973 SFCCA[22885:907] <UIProgressView: 0x1c5b51d0; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 5; layer = <CALayer: 0x1c5b5270>> at indexPath #5
2013-08-17 10:59:51.593 SFCCA[22885:907] <UIProgressView: 0x1c5aa1f0; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 2; layer = <CALayer: 0x1c5aa270>> at indexPath #2
2013-08-17 10:59:51.598 SFCCA[22885:907] <UIProgressView: 0x1c5b9860; frame = (20 248; 150 9); opaque = NO; tag = 3; layer = <CALayer: 0x1c5b9a30>> at indexPath #3
2013-08-17 10:59:51.983 SFCCA[22885:907] <UIProgressView: 0x1c5bca00; frame = (20 248; 150 9); hidden = YES; opaque = NO; layer = <CALayer: 0x1c5d1000>> at indexPath #0
2013-08-17 10:59:51.995 SFCCA[22885:907] <UIProgressView: 0x1c59c7c0; frame = (20 248; 150 9); hidden = YES; opaque = NO; tag = 1; layer = <CALayer: 0x1c5bb310>> at indexPath #1

Answer 1

经过2周的挣扎，管理解决这个问题。简单的解决方案，但我没想到它。

我有一个属性如下@property (strong, nonatomic) NSMutableArray *progressViewsArray;。不要忘记分配和初始化它。我是在viewDidLoad中完成的。

在collectionView:cellForItemAtIndexPath:中，我在返回单元格之前使用了以下逻辑。

for (UIProgressView *progressView in cell.contentView.subviews)
{
    if ([progressView isKindOfClass:[UIProgressView class]])
    {
        [progressView removeFromSuperview];
    }
}
for (UIProgressView *progressView in self.progressViewsArray)
{
    if (progressView.tag == indexPath.item)
    {
        [cell.contentView addSubview:progressView];
    }
}

在downloadButtonTapped:中，这是我创建UIProgressView实例的方式：

UIProgressView *progressView = [[UIProgressView alloc] initWithProgressViewStyle:UIProgressViewStyleDefault];
progressView.frame = CGRectMake(178, 180, 170, 9);
[progressView setTag:indexPath.item];
[cell.contentView addSubview:progressView];
[self.progressViewsArray addObject:progressView];

在AFNetworking的setDownloadProgressBlock（downloadButtonTapped:）中：

float progress = (float) totalBytesRead / totalBytesExpectedToRead;
[progressView setProgress:progress];

最后在AFNetworking的setCompletionBlock（downloadButtonTapped:）中：

NSMutableArray *progressViewsToDelete = [[NSMutableArray alloc] init];
for (UIProgressView *pv in self.progressViewsArray)
{
    if (pv.tag == indexPath.item)
    {
        [progressViewsToDelete addObject:pv];
    }
}
if (progressViewsToDelete.count > 0)
{
    [self.progressViewsArray removeObjectsInArray:progressViewsToDelete];
}
[self.collectionView reloadItemsAtIndexPaths:@[indexPath]]; // To reflect changes.

希望这能帮助将来的人，干杯！

Answer 2

您应该将所有视图添加到原型单元格中，并将其中一些设置为隐藏。但具体来说，在collectionView:cellForItemAtIndexPath:中，您应该设置所配置的所有视图的hidden属性，以便在需要时使其可见，并在不需要时隐藏它们。然后，无论细胞是新的还是重复使用都无关紧要，您始终可以保证正确的视图可见。

在您当前的解决方案中，您有一些逻辑可以阻止创建新的进度视图（如果已有）。但是，您实际上从未从单元格中删除任何进度视图。因此，当您重复使用单元格时，它仍可能具有进度视图作为子视图。使用隐藏视图或显示视图（并设置进度值）的方法可以避免这种情况。

Answer 3

我有类似的问题。我解决了它。您已在此方法中更改了单元格的子视图：- (IBAction)downloadButtonTapped:(id)sender，并且您未将此子视图更新为方法：collectionView:cellForItemAtIndexPath:。当重用单元格工作时，它只是从这个方法获取视图：collectionView:cellForItemAtIndexPath:，并且不包括在此方法之外更改的子视图，因此您应该在方法collectionView:cellForItemAtIndexPath:中执行某些操作来更新您的更改关于细胞的子视图。无论如何，我希望这可以帮助你。

UICollectionView - 在其他单元格中复制的子视图实例

问题：

编辑：

3 个答案: