如何将自定义单元格添加到UITableView的底部？

Question

我有一个UITableView,其中数据源是使用NSFetchRequest的 Core Data .核心数据包含从我的网站上的数据库下载的新闻项目.默认情况下,核心数据包含50个最新项目,当达到UITableView的底部时,旧项目是延迟下载的.

我正在使用这个tableView:numberOfRowsInSection方法处理这个问题,我在最后一节返回+1,这是我的"加载项目"单元格.在tableView:cellForRowAtIndexPath方法中,当IndexPath是最后一节中的最后一行时,我正在创建"正在加载项"单元格.

问题在于,当下载新数据时,之前是"加载项目"单元格的单元格现在是常规新闻项目单元格.但是当我从细胞中滚动并返回时,首先重新加载细胞.

我可以存储"装载项"单元格的indexPath,并在延迟加载完成后重新加载该单元格.但我想知道,如果存在更好的解决方案吗？

EDIT1:

这是我创建"加载项目"UITableViewCell的过程.

cell.textLabel.text = [NSString stringWithFormat:@"%@\u2026", NSLocalizedString(@"LOADING_MORE", nil)];

UIActivityIndicatorView *spinner = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];

UIImage *spacer = [UIImage imageNamed:@"Spacer"];

UIGraphicsBeginImageContext(spinner.frame.size);
[spacer drawInRect:CGRectMake(0,0,spinner.frame.size.width,spinner.frame.size.height)];
UIImage* resizedSpacer = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

cell.imageView.image = resizedSpacer;
[cell.imageView addSubview:spinner];
[spinner startAnimating];

EDIT2:

我正在尝试使用下面的代码"设计"footerView.目前,活动指示器位于左上角位置,标签不可见.

- (CGFloat)tableView:(UITableView *)tableView heightForFooterInSection:(NSInteger)section {
    NSInteger sectionsAmount = [tableView numberOfSections];
    if (section == sectionsAmount - 1) {
        return 20;
    }
    return 0;
}

- (UIView *)tableView:(UITableView *)tableView viewForFooterInSection:(NSInteger)section {
    NSInteger sectionsAmount = [tableView numberOfSections];
    if (section == sectionsAmount - 1) {
        if (_tableFooterView==nil) {
            UIView *view = [[UIView alloc] init];

            UIActivityIndicatorView *spinner = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];

            UIImage *spacer = [UIImage imageNamed:@"Spacer"];

            UIGraphicsBeginImageContext(spinner.frame.size);
            [spacer drawInRect:CGRectMake(0,0,spinner.frame.size.width,spinner.frame.size.height)];
            UIImage* resizedSpacer = UIGraphicsGetImageFromCurrentImageContext();
            UIGraphicsEndImageContext();

            UIImageView *imageView = [[UIImageView alloc] init];

            imageView.image = resizedSpacer;
            [imageView addSubview:spinner];
            [spinner startAnimating];

            [view addSubview:imageView];

            UILabel *label = [[UILabel alloc] init];
            label.text = [NSString stringWithFormat:@"%@\u2026", NSLocalizedString(@"LOADING_MORE", nil)];
            [view addSubview:label];

            _tableFooterView = view;
        }
        return self.tableFooterView;
    }
    return nil;
}

如何将UIView更改为如下图所示:

EDIT3:

这是我的setupTableFooterView,我正在为其分配视图tableFooterView.从viewDidLoad调用该方法.

- (void) setupTableFooterView {
    UIView *view = [[UIView alloc] init];

    UIActivityIndicatorView *spinner = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];

    UIImage *spacer = [UIImage imageNamed:@"Spacer"];

    UIGraphicsBeginImageContext(spinner.frame.size);
    [spacer drawInRect:CGRectMake(0,0,spinner.frame.size.width,spinner.frame.size.height)];
    UIImage* resizedSpacer = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    UIImageView *imageView = [[UIImageView alloc] init];

    imageView.image = resizedSpacer;
    [imageView addSubview:spinner];
    [spinner startAnimating];

    imageView.frame = CGRectMake(10, 11, 20, 20);
    [view addSubview:imageView];

    UILabel *label = [[UILabel alloc] init];
    label.text = [NSString stringWithFormat:@"%@\u2026", NSLocalizedString(@"LOADING_MORE", nil)];
    [label setFont:[UIFont italicSystemFontOfSize:13]];
    [label setFrame:CGRectMake(40, 0, 270, 43)];
    [view addSubview:label];

    self.tableView.tableFooterView = view;
}

Answer 1

使用UITableView tableFooterView替代该消息.这样你就不必弄乱部分/行结构了.

从UITableView参考:

tableFooterView

返回显示在表格下方的附件视图.

@property(nonatomic, retain) UIView *tableFooterView

讨论

默认值为nil.表格页脚视图与章节页脚不同.