ios - UITableViewCell 仅在滚动时正确布局

Question

我有一个带有自定义 UITableViewCells 的 UITableView。根据我从服务器收到的文本，单元格需要具有不同的高度。我相应地改变高度如下:

- (CGFloat)tableView:(UITableView *)tableView heightForRowAtIndexPath:(NSIndexPath *)indexPath
{
    if (indexPath.row == 0)
        return [self getHeightOfQuestion];
    else if (indexPath.row == 1)
        return 64.0f;
    else // ****** this is the cell in question!
        return [self getHeightOfAnswerAtIndexPath:indexPath];
    return 300.0f;
}

]- (CGFloat) getHeightOfAnswerAtIndexPath:(NSIndexPath*) indexPath
{
    CGRect answerFrame = CGRectZero;
    if ([QXTUtility currentOsVersion] >= 7.0f)
    {
        answerFrame = [[[[self.answerDetails objectForKey:kAnswers] objectAtIndex:indexPath.row-2] objectForKey:kAnswerText] boundingRectWithSize:CGSizeMake(242.0f, 900.0f) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:[UIFont fontWithName:@"Roboto-Light" size:14.0f]} context:nil];
    }
    else
    {
        CGSize answerSize = [[[[self.answerDetails objectForKey:kAnswers] objectAtIndex:indexPath.row-2] objectForKey:kAnswerText] sizeWithFont:[UIFont fontWithName:@"Roboto-Light" size:14.0f] constrainedToSize:CGSizeMake(242.0f, 500.0f) lineBreakMode:NSLineBreakByTruncatingTail];
        answerFrame.size = answerSize;
    }
    NSLog(@"Frame %@", NSStringFromCGRect(answerFrame));

    return answerFrame.size.height + 50;
}

它在 iOS6 上运行良好。但在 iOS7 中，我得到以下输出:

但是，如果我再次滚动 UITableView，单元格的布局就像这样:

这是我的cellForRowAtIndexPath:

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *answerCellIdentifier = @"QXTAnswerCell";

    QXTAnswerCell *answerCell = (QXTAnswerCell *)[tableView dequeueReusableCellWithIdentifier:answerCellIdentifier];
    if (answerCell == nil)
    {
        NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"QXTAnswerCell" owner:self options:nil];
        answerCell = [nib objectAtIndex:0];
    }
    [self setDataToAnswerCell:answerCell AtIndexPath:indexPath];
    [self layoutAnswerCell:answerCell AtIndexPath: indexPath];
    [answerCell setNeedsLayout];
    return answerCell;

- (void) layoutAnswerCell:(QXTAnswerCell*) answerCell
              AtIndexPath:(NSIndexPath*) indexPath
{
    CGRect answerCellFrame = answerCell.answer.frame;
    answerCellFrame.origin.y = answerCell.name.frame.origin.y + answerCell.name.frame.size.height + 6;
    if ([QXTUtility currentOsVersion] >= 7.0f)
    {
        answerCellFrame.size.height += 30.0f;
        answerCell.answer.lineBreakMode = NSLineBreakByWordWrapping;
    }
    answerCell.answer.frame = answerCellFrame;
    dispatch_async(dispatch_get_main_queue(), ^{
        [answerCell setNeedsLayout];
    });
}

请帮帮我。填充答案的数据源后，我将调用重新加载数据。谢谢。

更新

刚发现第一个 reloadData 在从服务器收到答案后不会被调用。

// Delegate from Network Class
- (void) answersReceivedWithDetails:(id)answerDetails
{
    NSLog(@"Answer Details %@", answerDetails);
    self.answerDetails = [[NSMutableDictionary alloc] initWithDictionary:answerDetails];
    [self.tableView reloadData];
    [self.tableView setNeedsDisplay];
}

这是单元格的约束:

Answer 1

以下是我为解决问题所做的工作。使用 IBOutlets 创建的 boundingRectWithSize 和 UILabels 存在一些问题。因此，我执行了上述操作，然后将其分配给使用代码创建的 UILabel 并将其添加到单元格中。一切都运行良好!

- (void) layoutAnswerCell:(QXTAnswerCell*) answerCell
              AtIndexPath:(NSIndexPath*) indexPath
{
    if ([QXTUtility currentOsVersion] >= 7.0f)
    {
        [answerCell.answer removeFromSuperview];
        NSString *answerString = <your string>
        CGRect answerFrame = [answerString boundingRectWithSize:CGSizeMake(242.0f, 900.0f) options:NSStringDrawingUsesLineFragmentOrigin attributes:@{NSFontAttributeName:[UIFont fontWithName:@"Roboto-Light" size:14.0f]} context:nil];
        answerFrame.origin.x = 20.0f;

        answerFrame.origin.y = answerCell.name.frame.origin.y + answerCell.name.frame.size.height + 6;
        answerFrame.size.height = ceilf(answerFrame.size.height);
        answerFrame.size.height += 30.0f;
        answerCell.answer.lineBreakMode = NSLineBreakByTruncatingTail;
        answerCell.answer.frame = answerFrame;

        UILabel *newLabel = [[UILabel alloc] initWithFrame:answerFrame];
        [newLabel setFont:[UIFont fontWithName:@"Roboto-Light" size:14.0f]];
        newLabel.text = answerString;
        newLabel.numberOfLines = 0;
        [answerCell.contentView addSubview:newLabel];
        [answerCell setNeedsDisplay];
    }
}

看看这对其他人是否有效。如果是这样，我会接受这个答案。但它确实帮我完成了工作。