更改 UITableViewCell 附件后 UITableViewCellAccessoryDe​​tailDisclosureButton 消失

Question

我有一个UITableView，其中包含带有图像、文本和披露按钮的单元格。我正在像这样加载单元格：

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

    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:cellIdentifier];
    if(!cell) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:cellIdentifier];
    }

    if ([indexPath row] == [[self multas] count]) {
        [[cell textLabel] setText:@"Carregar mais..."];
    } 
    else 
    {
        Multa *multa = [self.multas objectAtIndex:indexPath.row];

        NSString *dataIsolada = [[NSString stringWithFormat:[multa dataOcorrencia]] substringWithRange:NSMakeRange(0, 10)];

        [[cell textLabel] setText:[NSString stringWithFormat:dataIsolada]];
        [[cell detailTextLabel] setText:[multa descricao]];
        [cell.imageView setImageWithURL:[NSURL URLWithString:[multa fotoURL]]
                       placeholderImage:[UIImage imageNamed:@"carregando.jpeg"]];
        [cell.imageView setContentMode: UIViewContentModeScaleAspectFit];
        [cell setAccessoryType:UITableViewCellAccessoryDetailDisclosureButton];
    }

    return cell;
}

当用户点击显示按钮时，我将显示按钮切换为活动指示器，然后使用导航控制器将另一个视图推送到屏幕：

- (void)carregarDetalhesMulta:(UITableView *)tableView comMulta:(Multa *)multa 
{
    DetalheMultaViewController *form = [[DetalheMultaViewController alloc] initWithMulta:multa];
    form.delegate = self;

    UINavigationController *navigation = [[UINavigationController alloc] initWithRootViewController:form];

    [self presentModalViewController:navigation animated:YES];
}

- (void) tableView: (UITableView *) tableView accessoryButtonTappedForRowWithIndexPath: (NSIndexPath *) indexPath
{
    UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
    UIActivityIndicatorView *spinner = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle: UIActivityIndicatorViewStyleGray];
    spinner.frame = CGRectMake(0, 0, 24, 24);
    cell.accessoryView = spinner;
    [spinner startAnimating];

    Multa *multa = [self.multas objectAtIndex:indexPath.row];

    double delayInSeconds = 0.1;
    dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, delayInSeconds * NSEC_PER_SEC);

    dispatch_after(popTime, dispatch_get_main_queue(), ^(void){

       [spinner stopAnimating];
       [self carregarDetalhesMulta:tableView comMulta:multa];
       [cell setAccessoryType:UITableViewCellAccessoryDetailDisclosureButton];
    });

}

请注意，我最后将附件改回了一个披露按钮。问题是：当我返回（通过点击返回按钮）到包含UITableView 的视图时，我点击的行没有显示任何披露按钮或活动指示器。我做错了什么？在无需重新加载表格视图的情况下切换这些控件的更好方法是什么？

Answer 1

accessoryView 属性优先于accessoryType 属性。如果您将accessoryView 设置为nil，您将再次看到附件按钮。

Answer 2

这是我从问题中了解到的：您希望附件视图成为一个披露按钮，当点击该按钮时，它会成为一个活动指示器。短暂延迟后，您想推送到新的视图控制器。

我会这样做：

1. 将情节提要中的原型单元设置为 Accessory:none。
2. 从你的视图控制器中添加一个 push segue 到你想要的目标 vc，给它一个标识符，比如 @"MyPushSegue"

将附件视图添加到 cellForRowAtIndexPath 中的单元格（如果没有的话）：

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:@"Cell"];
    // the rest of your cellForRowAtIndexPath

     if (!cell.accessoryView)
        cell.accessoryView = [self createAccessoryView];

    return cell;
}

以这种方式创建附件视图（假设为 ARC）：

- (UIView *)createAccessoryView {

    UIView *accessoryView = [[UIView alloc] initWithFrame:CGRectZero];
    UIButton *disclosureButton = [UIButton buttonWithType:UIButtonTypeDetailDisclosure];

    disclosureButton.tag = 100;
    [disclosureButton addTarget:self action:@selector(pressedAccessory:) forControlEvents:UIControlEventTouchUpInside];

    UIActivityIndicatorView *aiv = [[UIActivityIndicatorView alloc] initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
    aiv.tag = 101;
    aiv.alpha = 0.0;
    aiv.center = disclosureButton.center;

    accessoryView.bounds = disclosureButton.bounds;
    [accessoryView addSubview:aiv];
    [accessoryView addSubview:disclosureButton];
    return accessoryView;
}

上面的公开按钮在按下按钮时触发一个方法。此方法应更改选择器视图的状态并触发您在情节提要中设置的 push segue：

- (void)pressedAccessory:(UIButton *)sender {

    UIView *accessoryView = sender.superview;
    [self setAccessoryView:accessoryView waiting:YES];

    // let the user see the spinner for 1 seconds
    dispatch_time_t popTime = dispatch_time(DISPATCH_TIME_NOW, 1 * NSEC_PER_SEC);
    dispatch_after(popTime, dispatch_get_main_queue(), ^(void) {
        [self performSegueWithIdentifier:@"MyPushSegue" sender:self];
        [self setAccessoryView:accessoryView waiting:NO];
    });
}

最后，为了解决您遇到的问题，我们不会用微调器替换附件视图，而是通过隐藏/显示按钮和隐藏/显示微调器来改变它的外观，具体取决于我们想要的状态：

- (void)setAccessoryView:(UIView *)accessoryView waiting:(BOOL)waiting {

    UIButton *disclosureButton = (UIButton *)[accessoryView viewWithTag:100];
    UIActivityIndicatorView *aiv = (UIActivityIndicatorView *)[accessoryView viewWithTag:101];
    [UIView animateWithDuration:0.1 animations:^{
        disclosureButton.alpha = (waiting)? 0.0 : 1.0;
        aiv.alpha = (waiting)? 1.0 : 0.0;
    }];

    if (waiting) [aiv startAnimating]; else [aiv stopAnimating];
}