当表格向上滚动并返回到该单元格时，UITableViewCell 背景图像问题

Question

当用户向下和向上滚动表格时，我面临 UITableViewCell 设置问题。一旦分组表滚动到另一个单元格并返回到该单元格，单元格就会丢失更改（在 -didSelectRowAtIndexPath 中设置的红色/绿色背景图像）。

我使用下面的代码在两个部分中显示一个问题和 4 个答案选项。

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    NSString *kCustomCellID = [NSString stringWithFormat:@"CustomCellID%d", ((100 * indexPath.section) + indexPath.row)];

    UITableViewCell *cell = nil;//[tableView dequeueReusableCellWithIdentifier:kCustomCellID];

    if (cell == nil) {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:kCustomCellID] autorelease];
        cell.selectionStyle = UITableViewCellSelectionStyleNone;
    }

    if (indexPath.section == 0) {
        cell.textLabel.text = questionText;
        cell.textLabel.textAlignment = UITextAlignmentCenter;
        cell.textLabel.font = FONT_QUESTIONTEXT;
        cell.textLabel.numberOfLines = 0;
    }
    else {
        cell.textLabel.text = [self.answerChoices objectAtIndex:indexPath.row];
        cell.textLabel.font = FONT_ANSWERTEXT;
        cell.textLabel.numberOfLines = 0;

        ConfigurationBase *configBase = [[ConfigurationBase alloc] initWithConfigurationType:kConfigTypeQuiz];

        NSString *backgroundImageName = [configBase.configInfo valueForKey:CKEY_IMG_ANSWER_BACKGROUND];
        NSString *leftImage = [configBase.configInfo valueForKey:[choicesLeftImages objectAtIndex:indexPath.row]];
        [configBase release];

        cell.backgroundColor = [UIColor clearColor];
        UIImageView *bgView = [[UIImageView alloc] initWithFrame:cell.frame];
        bgView.image = [UIImage imageNamed:backgroundImageName];
        cell.backgroundView = bgView;
        [bgView release];

        cell.imageView.image = [UIImage imageNamed:leftImage];
    }

    return cell;
}

并且，当用户选择其中一个选项时，我将背景颜色正确和错误的选择更改为绿色和红色。下面是更改两行背景的代码。

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
    if (indexPath.section == 1) {   // Answer choice section.
        NSString *correctAnswerStr = [quizSession fetchCorrectAnswer];
        NSInteger correctAnswerIndex = -1;
        ConfigurationBase *configBase = [[ConfigurationBase alloc] initWithConfigurationType:kConfigTypeQuiz];

        NSString *correctAnsImageName = [configBase.configInfo valueForKey:CKEY_IMG_ANSWER_CORRECT_BACKGROUND];
        NSString *wrongAnsImageName = [configBase.configInfo valueForKey:CKEY_IMG_ANSWER_WRONG_BACKGROUND];
        [configBase release];

        UITableViewCell *answerCell = [tableView cellForRowAtIndexPath:indexPath];

        answerCell.backgroundColor = [UIColor clearColor];
        UIImageView *bgView = [[UIImageView alloc] initWithFrame:answerCell.frame];
        bgView.image = [UIImage imageNamed:wrongAnsImageName];
        answerCell.backgroundView = bgView;
        [bgView release];

        for (NSString *answerChoice in answerChoices) {
            ++correctAnswerIndex;

            if ([answerChoice isEqualToString:correctAnswerStr]) {
                // Correct Index obtained, so set the background color for it.
                NSIndexPath *correctIndexPath = [NSIndexPath indexPathForRow:correctAnswerIndex
                                                                   inSection:indexPath.section];
                UITableViewCell *correctAnswerCell = [tableView cellForRowAtIndexPath:correctIndexPath];

                correctAnswerCell.backgroundColor = [UIColor clearColor];
                UIImageView *bgView = [[UIImageView alloc] initWithFrame:correctAnswerCell.frame];
                bgView.image = [UIImage imageNamed:correctAnsImageName];
                correctAnswerCell.backgroundView = bgView;
                [bgView release];

                break;
            }
        }

        // Enable the 'next' button, allowing user to go for next question.
        self.navigationItem.rightBarButtonItem.enabled = YES;
        // Disable selection of answer until user go to next question.
    tableView.allowsSelection = NO;
}

任何人都可以帮助我吗？ TIA。

问候。

Answer 1

您检索有关背景图像名称的信息的方法非常复杂且容易出错。请通过在适当的位置插入 NSLog 或检查调试器来确保一切按预期工作。

处理单元格的 backgroundView 属性时，您必须将此代码放入 tableView:willDisplayCell:forRowAtIndexPath: 而不是 cellForRowAtIndexPath 中。更简单的方法将再次节省您的时间。