Iphone UITableView加载单元格时滚动速度慢的问题

我的tableview单元格滚动速度有问题。您可以看到，当退出队列并重用单元时，它会挂起。下面是我用来创建单元格的代码。我使用2个自定义单元格，一个单元格是如果有图像，另一个单元格是如果用户没有附加图像。如有任何见解，将不胜感激。我还应该补充一点，我想在单元格之间添加一个空格，所以基本上我创建了一个包含单个单元格的新部分，这就是为什么您总是在我的代码indexPath.section中看到

    - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
    {
        static NSString *imageCell = @"ShameImage";
        static NSString *noImageCell = @"ShameNoImageCell";
        static NSString *noCell = @"NoCell";

        UITableViewCell *cell = [self.tableView dequeueReusableCellWithIdentifier:noCell];

        if ([[blobID objectAtIndex:indexPath.section] isEqualToNumber:[NSNumber numberWithInt:1]])
        {
            ShameViewCell *cell = (ShameViewCell *)[self.tableView dequeueReusableCellWithIdentifier:imageCell];
            if (cell == nil)
            {
                NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"ShameImageCell" owner:self options:nil];
                cell = [nib objectAtIndex:0];
                CALayer *cellImageView = [cell.imageView layer];
                [cellImageView setMasksToBounds:YES];
                [cellImageView setCornerRadius:10.0];
                IndicatorImageView *iiv = [[IndicatorImageView alloc] initWithFrame:CGRectMake(0, 0, 88, 88)];
                [iiv setShameID:[[shameID objectAtIndex:indexPath.section] stringValue]];
                iiv.tag = 999;
                [iiv loadImageFromURL];
                [cell.imageView addSubview:iiv];
                cell.imageView.userInteractionEnabled = YES;
                UITapGestureRecognizer *tapImage = [[UITapGestureRecognizer alloc]
                                                    initWithTarget:self action:@selector(openPicture:)];
                tapImage.numberOfTapsRequired = 1;
                [cell.imageView addGestureRecognizer:tapImage];

                [cell.contentView.layer setCornerRadius:10];
                [cell.contentView setBackgroundColor:[UIColor blackColor]];
                [cell.contentView setAlpha:0.7f];
                UIColor *insideColor = [UIColor colorWithRed:color_red green:color_green blue:color_blue alpha:1];

                cell.lastShame.contentInset = UIEdgeInsetsMake(-11, -8, 0, 0);
                [cell.lastShame setTextColor:insideColor];
                [cell.lastShame setFont:[UIFont fontWithName:text_font_name size:14]];
                cell.lastShame.text = [userShame objectAtIndex:indexPath.section];

                [cell.shameDate setTextColor:insideColor];
                [cell.shameDate setFont:[UIFont fontWithName:text_font_name size:11]];
                cell.shameDate.text = [createDt objectAtIndex:indexPath.section];
                [cell.userLabel setTextColor:insideColor];
                [cell.userLabel setFont:[UIFont fontWithName:text_font_name size:11]];
                cell.userLabel.text = [@"Post By: " stringByAppendingString:[userName objectAtIndex:indexPath.section]];
                [cell.lastShame setBackgroundColor:[UIColor clearColor]];

                return cell;
            }

        }else
        {
            ShameNoImage *cell = (ShameNoImage *)[self.tableView dequeueReusableCellWithIdentifier:noImageCell];
            if (cell == nil)
            {
                NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"ShameNoImageCell" owner:self options:nil];
                cell = [nib objectAtIndex:0];
                CALayer *cellImageView = [cell.imageView layer];
                [cellImageView setMasksToBounds:YES];
                [cellImageView setCornerRadius:10.0];
                [cellImageView setBorderWidth:1.0];
                [cellImageView setBorderColor:[[UIColor whiteColor] CGColor]];
                [cell.contentView.layer setCornerRadius:10];
                [cell.contentView setBackgroundColor:[UIColor blackColor]];
                [cell.contentView setAlpha:0.7f];
                UIColor *insideColor = [UIColor colorWithRed:color_red green:color_green blue:color_blue alpha:1];

                cell.shameLabel.contentInset = UIEdgeInsetsMake(-11, -8, 0, 0);
                [cell.shameLabel setTextColor:insideColor];
                [cell.shameLabel setFont:[UIFont fontWithName:text_font_name size:14]];
                cell.shameLabel.text = [userShame objectAtIndex:indexPath.section];

                [cell.dateLabel setTextColor:insideColor];
                [cell.dateLabel setFont:[UIFont fontWithName:text_font_name size:11]];
                cell.dateLabel.text = [createDt objectAtIndex:indexPath.section];
                [cell.userLabel setTextColor:insideColor];
                [cell.userLabel setFont:[UIFont fontWithName:text_font_name size:11]];
                cell.userLabel.text = [@"Post By: " stringByAppendingString:[userName objectAtIndex:indexPath.section]];
                [cell.shameLabel setBackgroundColor:[UIColor clearColor]];
                return cell;
            }
        }

        return cell;
    }

---

跳出的第一件事是调用

setCornerRadius

。一个快速的测试是去掉拐角半径，看看这是否有助于你的速度。如果这是你的问题，你将不得不切换到绘图与CG和一个

UIBezierPath

---

接下来要看的是透明度和正在使用的子视图的数量。上面发布的内容很难说，但是更多的子视图，尤其是alpha，意味着更多的合成工作。但根据你的设计，这可能很难做到，但用CG或使用图像绘图会有所帮助。

我想出来了。我正在重建和绘制每一个细胞。我需要在单元格的子类中设置reuseIdentifier，然后将表的构建更改为这样

    - (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
    {
        static NSString *imageCell = @"ShameImage";
        static NSString *noImageCell = @"ShameNoImageCell";

        ShameViewCell *iCell = (ShameViewCell *)[self.tableView dequeueReusableCellWithIdentifier:imageCell];
        ShameNoImage *niCell = (ShameNoImage *)[self.tableView dequeueReusableCellWithIdentifier:noImageCell];

        if ([[blobID objectAtIndex:indexPath.section] isEqualToNumber:[NSNumber numberWithInt:1]])
        {
            if (iCell == nil)
            {
                NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"ShameImageCell" owner:self options:nil];
                iCell = [nib objectAtIndex:0];
                CALayer *cellImageView = [iCell.imageView layer];
                [cellImageView setMasksToBounds:YES];
                IndicatorImageView *iiv = [[IndicatorImageView alloc] initWithFrame:CGRectMake(0, 0, 88, 88)];
                [iiv setShameID:[[shameID objectAtIndex:indexPath.section] stringValue]];
                iiv.tag = 999;
                [iiv loadImageFromURL];
                [iCell.imageView addSubview:iiv];
                iCell.imageView.userInteractionEnabled = YES;
                UITapGestureRecognizer *tapImage = [[UITapGestureRecognizer alloc]
                                                    initWithTarget:self action:@selector(openPicture:)];
                tapImage.numberOfTapsRequired = 1;
                [iCell.imageView addGestureRecognizer:tapImage];

                [iCell.contentView setBackgroundColor:[UIColor blackColor]];
                [iCell.contentView setAlpha:0.7f];
                UIColor *insideColor = [UIColor colorWithRed:color_red green:color_green blue:color_blue alpha:1];

                iCell.lastShame.contentInset = UIEdgeInsetsMake(-11, -8, 0, 0);
                [iCell.lastShame setTextColor:insideColor];
                [iCell.lastShame setFont:[UIFont fontWithName:text_font_name size:14]];
                iCell.lastShame.text = [userShame objectAtIndex:indexPath.section];

                [iCell.shameDate setTextColor:insideColor];
                [iCell.shameDate setFont:[UIFont fontWithName:text_font_name size:11]];
                iCell.shameDate.text = [createDt objectAtIndex:indexPath.section];
                [iCell.userLabel setTextColor:insideColor];
                [iCell.userLabel setFont:[UIFont fontWithName:text_font_name size:11]];
                iCell.userLabel.text = [@"Post By: " stringByAppendingString:[userName objectAtIndex:indexPath.section]];

                return iCell;
            }else
            {
                [[iCell.imageView viewWithTag:999] removeFromSuperview];
                IndicatorImageView *iiv = [[IndicatorImageView alloc] initWithFrame:CGRectMake(0, 0, 88, 88)];
                [iiv setShameID:[[shameID objectAtIndex:indexPath.section] stringValue]];
                iiv.tag = 999;
                [iiv loadImageFromURL];
                [iCell.imageView addSubview:iiv];
                iCell.lastShame.text = [userShame objectAtIndex:indexPath.section];
                iCell.shameDate.text = [createDt objectAtIndex:indexPath.section];
                iCell.userLabel.text = [@"Post By: " stringByAppendingString:[userName objectAtIndex:indexPath.section]];

                return iCell;
            }

        }else
        {
            if (niCell == nil)
            {
                NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"ShameNoImageCell" owner:self options:nil];
                niCell = [nib objectAtIndex:0];
                [niCell.contentView setBackgroundColor:[UIColor blackColor]];
                [niCell.contentView setAlpha:0.7f];
                UIColor *insideColor = [UIColor colorWithRed:color_red green:color_green blue:color_blue alpha:1];

                niCell.shameLabel.contentInset = UIEdgeInsetsMake(-11, -8, 0, 0);
                [niCell.shameLabel setTextColor:insideColor];
                [niCell.shameLabel setFont:[UIFont fontWithName:text_font_name size:14]];
                niCell.shameLabel.text = [userShame objectAtIndex:indexPath.section];

                [niCell.dateLabel setTextColor:insideColor];
                [niCell.dateLabel setFont:[UIFont fontWithName:text_font_name size:11]];
                niCell.dateLabel.text = [createDt objectAtIndex:indexPath.section];
                [niCell.userLabel setTextColor:insideColor];
                [niCell.userLabel setFont:[UIFont fontWithName:text_font_name size:11]];
                niCell.userLabel.text = [@"Post By: " stringByAppendingString:[userName objectAtIndex:indexPath.section]];
                return niCell;
            }else
            {
                niCell.shameLabel.text = [userShame objectAtIndex:indexPath.section];
                niCell.dateLabel.text = [createDt objectAtIndex:indexPath.section];
                niCell.userLabel.text = [@"Post By: " stringByAppendingString:[userName objectAtIndex:indexPath.section]];
                return niCell;
            }
        }
        return niCell;
    }

---

如果

loadImageFromURL:

调用同步点击网络，那么您的滚动速度缓慢的主要原因之一。请参阅指示符号MagView确实异步加载它们，并在下载期间将活动指示符号放入单元格中。此外，我还应该提到，它缓存了图像，在回拉缓存的图像时，我仍然有缓慢的滚动。使用Instruments的时间分析器来查看是什么导致了最大的延迟-它可以让您深入到导致延迟/延迟的实际代码行，您应该在单元格中使用不透明子视图，并避免使用

clearColor

。这无疑会扼杀滚动性能。时间剖析器似乎把核心基础指向时间消费者。我已经去掉了clearColor和rounded radius，看看它是否有所改进，它似乎更好一些，但当它必须切换到不同的单元格类型时，我仍然看到一个挂起的问题。你有任何关于如何使用UIBezierPath的示例吗？下面是一个示例。那是你问题的根源吗？