uitableview重新加载数据缓存？

Question

我在使用 UITableView 和 reloadData 方法时遇到一些问题。

当单击刷新按钮时，我正在刷新 tableView，其中数据库中的最后一个信息按降序排列，因此最新的项目应出现在第一个位置。

我的表格视图中的每个单元格都充满了自定义标签和 uiimageviews。

嗯...问题是，当我按下刷新按钮并找到新数据时，前 5 行（显示屏中显示的行）不会更新，但后面的行会更新。但是，如果我按下前 5 行中的任何一行，它们就会使用新数据正确调用 tableView:didSelectRowAtIndexPath: 方法。

所以，问题是表视图的前 5 行的“视觉”内容没有被更新。

任何人都可以帮我解决这个问题吗？

谢谢！

代码：

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSString *CellIdentifier = [ NSString stringWithFormat: @"%d:%d", [ indexPath indexAtPosition: 0 ], [ indexPath indexAtPosition:1 ]];

    UITableViewCell *cell = [ tableView dequeueReusableCellWithIdentifier: CellIdentifier];

    if (cell == nil) {
        cell = [[[UITableViewCell alloc] initWithFrame: CGRectZero reuseIdentifier: CellIdentifier] autorelease];

        // Configure the cell...
        cell.accessoryType=UITableViewCellAccessoryDisclosureIndicator;
        Activity *activity = [[self.activities valueForKey:[[[self.activities allKeys] sortedArrayUsingSelector:@selector(localizedCaseInsensitiveCompare:)] objectAtIndex:indexPath.section]] objectAtIndex:indexPath.row];
        cell.textLabel.text=@"";
        //Mostramos el nombre
        UILabel *label= [[UILabel alloc] initWithFrame:CGRectMake(60, -5, 200, 34)];
        label.text = [activity name];
        label.font = [UIFont boldSystemFontOfSize:17];
        label.backgroundColor = [UIColor clearColor];
        [cell addSubview:label];
        [label release];

        //Mostramos la imagen
        UIImageView *leftImage = [[UIImageView alloc] initWithFrame:CGRectMake(5, 3, 50, 50)];
        [cell addSubview:leftImage];


        UITextView *textView=[[UITextView alloc] initWithFrame:CGRectMake(60, 25, 200, 38)];
        textView.editable = NO;
        textView.backgroundColor = [UIColor clearColor];
        textView.textColor = [UIColor grayColor];
        textView.font = [UIFont systemFontOfSize:12.0];
        textView.contentInset = UIEdgeInsetsMake(-8,-8,0,0);
        textView.userInteractionEnabled=NO;
        [cell addSubview:textView];

        switch ([activity notType]) {
            case 0:
                textView.text = [NSString stringWithFormat:NSLocalizedString(@"requestPUSH",@""),[activity name]];
                leftImage.image = [UIImage imageNamed:@"ios.png"];
                break;
            case 1:
                textView.text = [NSString stringWithFormat:NSLocalizedString(@"MPCreatedPushString",@""),[activity name],[activity nameItem]];
                leftImage.image = [UIImage imageNamed:@"mpNew.png"];
                break;
            case 2:
                textView.text = [NSString stringWithFormat:NSLocalizedString(@"MPUpdatedPushString",@""),[activity name],[activity nameItem]];
                leftImage.image = [UIImage imageNamed:@"mpUpdated.png"];
                break;
            case 3:
                textView.text = [NSString stringWithFormat:NSLocalizedString(@"MPDeletedPushString",@""),[activity name],[activity nameItem]];
                leftImage.image = [UIImage imageNamed:@"ios.png"];
                break;
            case 4:
                textView.text = [NSString stringWithFormat:NSLocalizedString(@"MPGuestConfirmationPUSHString",@""),[activity name],[activity nameItem]];
                leftImage.image = [UIImage imageNamed:@"attend.png"];
                break;
            case 5:
                if ([[activity message] isEqualToString:@"noData"]) {
                    textView.text = [NSString stringWithFormat:NSLocalizedString(@"ShoutPushString",@""),[activity name]];
                }else{
                    textView.text = [NSString stringWithFormat:NSLocalizedString(@"ShoutPushStringWithData",@""),[activity name], [activity message]];
                }
                UIImage *contactImage = [UIImage imageWithData:[[activity person] pic]];
                if (contactImage!=nil) {
                    leftImage.image = contactImage;
                    //redondeamos bordes
                    CALayer * l = [leftImage layer];
                    [l setMasksToBounds:YES];
                    [l setCornerRadius:5.0];
                }else{
                    leftImage.image = [UIImage imageNamed:@"ios.png"];
                }
                break;
            case 6:
                textView.text = [NSString stringWithFormat:NSLocalizedString(@"CheckinPushString",@""),[activity name],[activity nameItem]];
                leftImage.image = [UIImage imageNamed:@"ios.png"];
                break;
            case 7:
                textView.text = [NSString stringWithFormat:NSLocalizedString(@"MPGuestRejectionPUSHString",@""),[activity name],[activity nameItem]];
                leftImage.image = [UIImage imageNamed:@"reject.png"];
                break;
            default:
                break;
        }
        [leftImage release];
        [textView release];


        //Mostrar fecha
        double timestamp = [[activity datetime] doubleValue]/1000;
        NSString *dateShow;

        NSDate *datetime = [NSDate dateWithTimeIntervalSince1970:timestamp];
        NSDateFormatter *dateFormat = [[NSDateFormatter alloc] init];
        [dateFormat setDateFormat:@"HH:mm"];
        dateShow=[dateFormat stringFromDate:datetime];

        UILabel *label2= [[UILabel alloc] initWithFrame:CGRectMake(240, 0, 70, 20)];
        label2.text = dateShow;
        label2.textAlignment = UITextAlignmentRight;
        label2.font = [UIFont systemFontOfSize:12];
        label2.backgroundColor = [UIColor clearColor];
        label2.textColor = [UIColor blueColor];
        [cell addSubview:label2];
        [label2 release];

    }

    return cell;
}

Answer 1

嗯，所以你给每个单元格一个唯一的单元格标识符。你有理由这样做吗？
大多数人试图以这种方式修补他们对 iOS 表视图的误解......

当您重新加载表时，此调用 UITableViewCell *cell = [ tableView dequeueReusableCellWithIdentifier: CellIdentifier];
将为您提供一个可重复使用的单元格（读取已包含内容）。

但您的代码仅适用于“新鲜”单元格： if (cell == nil) {
，你只是还没有准备好应对这种情况......