UITableView不滚动平滑由于removeFromSuperview

Question

是什么让UITableView上的滚动如此不稳定?在我看来，遵循代码是罪魁祸首。我很难用别的东西来代替这个逻辑。

for (UIView *view in cell.contentView.subviews) {
[view removeFromSuperview]; }

这就是我正在做的。

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
for (UIView *view in cell.contentView.subviews) {
    [view removeFromSuperview];
}
BGMArticleAbstract *articleAbstract = [self.section.articleAbstracts objectAtIndex:indexPath.row];
[cell.contentView addSubview:[self getHedlineFromArticleAbstract:articleAbstract]];
[cell.contentView addSubview:[self getThumbnailImageFromArticleAbstract:articleAbstract]];
[cell.contentView addSubview:[self getAbstractParaFromArticleAbstract:articleAbstract]];
cell.selectionStyle = UITableViewCellSelectionStyleNone;
return cell; }

我正在做，addSubview到contentview因为我正在创建一个动态单元格高度。有什么方法可以让这个滚动视图流畅运行吗?谢谢你的帮助。

Answer 1

您应该根据需要设计您的单元格。添加标签和任何你需要的单元格，然后改变这些已经可用的子视图的内容。
如果需要显示图像，只需向单元格添加一次UIImageView，并仅更改其图像属性。对于文本字段等也是如此。

你这样做的方式使内置缓存无用，因为你重新生成所有的子视图一次又一次。

为了进一步提高性能，您可以自己绘制单元格。

Apple有一个非常好的示例项目:http://developer.apple.com/library/ios/samplecode/AdvancedTableViewCells/介绍/Intro.html

Answer 2

您是对的，问题是由您返回单元格的方式引起的。正确的格式如下:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
    }
    // see if cell contains our image views.  A reused cell will, but a new cell won't
    UIImageView *imageViewA = (UIImageView *)[cell viewWithTag:32];
    UIImageView *imageViewB = (UIImageView *)[cell viewWithTag:33];
    UIImageView *imageViewC = (UIImageView *)[cell viewWithTag:34];
    if (!imageViewA) {
        // the cell must be new, so create it's image views
        // you should be able to borrow most of this code from your getHeadline/thumbnail/etc methods.
        // the good news is that this relatively expensive code runs only for new
        // cells and there are only a few of those - only enough to fill the visible frame
        imageViewA = [[UIImageView alloc] initWithFrame:CGRectMake(/* frame it here */)];
        [cell.contentView addSubview:imageViewA];
        imageViewA.tag = 32;
        imageViewB = [[UIImageView alloc] initWithFrame:CGRectMake(/* frame it here */)];
        [cell.contentView addSubview:imageViewB];
        imageViewB.tag = 33;
        imageViewC = [[UIImageView alloc] initWithFrame:CGRectMake(/* frame it here */)];
        [cell.contentView addSubview:imageViewC;
        imageViewC.tag = 34;
        // this too, need only be done upon creation
        cell.selectionStyle = UITableViewCellSelectionStyleNone;
    }
    // now, whether it's a new cell or a reused cell, we have image views 
    BGMArticleAbstract *articleAbstract = [self.section.articleAbstracts objectAtIndex:indexPath.row];
    // change your methods getHeadline... getThumbnail... etc to answer UIImages
    // not UIImageViews, which are setup only for new cells
    imageViewA.image = [self getHedlineFromArticleAbstract:articleAbstract]];
    imageViewB.image = [self getThumbnailImageFromArticleAbstract:articleAbstract]];
    imageViewC.image = [self getAbstractParaFromArticleAbstract:articleAbstract]];
    // as a side note, once you get these methods returning images (more like model objects)
    // rather than image views (view objects) they might be more appropriately placed
    // in the BGMArticleAbstract class rather than the view controller
    return cell;
}