反转数组内容？

Question

我正在用信息填充表格视图，但希望它反向填充，以便任何新添加的单元格（新电子邮件）都会出现在顶部，而不是底部。

我做错了什么？

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

    MailCell *cell = (MailCell *)[tableView dequeueReusableCellWithIdentifier:simpleTableIdentifier];
    if (cell == nil)
    {
        NSArray *nib = [[NSBundle mainBundle] loadNibNamed:@"MailCell" owner:self options:nil];
        cell = [nib objectAtIndex:0];

        // SLICK
        // Anything that should be the same on EACH cell should be here.

        UIView *myBackView = [[UIView alloc] initWithFrame:cell.frame];
        myBackView.backgroundColor = [UIColor colorWithRed:15.0/255.0 green:140.0/255.0 blue:198.0/255.0 alpha:1];
        cell.selectedBackgroundView = myBackView;

        cell.selectionStyle = UITableViewCellSelectionStyleGray;
        cell.messageText.textAlignment = NSTextAlignmentLeft;
        cell.messageText.lineBreakMode = NSLineBreakByTruncatingTail;
    }

    NSUInteger row = [indexPath row];

    // Extract Data

    // Use the message object instead of the multiple arrays.

    CTCoreMessage *message = [[self allMessages] objectAtIndex:row];

    // Sender

    CTCoreAddress *sender = [message sender];
    NSString *senderName = [sender name];

    // Subject

    NSString *subject = [message subject];
    if ([subject length] == 0)
    {
        subject = @"(No Subject)";
    }

    // Body

    BOOL isPlain = YES;
    NSString *body = [message bodyPreferringPlainText:&isPlain];
    body = [body stringByReplacingOccurrencesOfString:@"\n" withString:@" "];
    body = [body stringByReplacingOccurrencesOfString:@"\r" withString:@" "];

    // Populate Cell

    [[cell nameText] setText:senderName];
    [[cell subjectField] setText:subject];
    [[cell messageText] setText:body];

    if ([message isUnread])
    {
        UIColor *myColor = [UIColor colorWithRed:15.0/255.0 green:140.0/255.0 blue:198.0/255.0 alpha:1.0];
        cell.nameText.textColor = myColor;
    }
    else
    {
        cell.nameText.textColor = [UIColor blackColor];
    }

    return cell;

}

我是如何加载数组的：

- (NSMutableArray *)allMessages
{
    if (_allMessages == nil)
    {
        _allMessages = [[NSMutableArray alloc] init];
    }
    return _allMessages;
}

Answer 1

您正在从 NSArray 索引[indexPath row] 中拉取，这意味着您从索引 0 开始并转到 n。这意味着您的顺序不是相反的。你需要先反转你的数组。一个简单的方法是：

- (void)viewWillAppear:(BOOL)animated
{
    NSArray *allMessages = [self allMessages];
    NSArray* reversedMessages = [[allMessages reverseObjectEnumerator] allObjects];
}

然后在你的cellForRowAtIndexPath 方法中你可以这样做：

CTCoreMessage *message = [reversedMessages objectAtIndex:row];