3

我正在尝试显示一个包含 2 个部分的表格视图。第一部分将始终有 1 行，第二部分将具有与数据点一样多的行。我正在使用核心数据和以下 tableView:numberOfRowsInSection: 方法...

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    if (section == 0) {
        return 1;
    } else {
        id <NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController sections] objectAtIndex:section];
        return [sectionInfo numberOfObjects];
    }
}

但是，我收到以下错误：

由于未捕获的异常“NSRangeException”而终止应用程序，原因：“ * -[__NSArrayM objectAtIndex:]: index 1 beyond bounds [0 .. 0]”

任何帮助将不胜感激。谢谢。

新的 - - - - - - - - - - - - - - - - - - - - - - - - - ------------------------------

这是相关方法的当前实现：

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    if (section == 0) {
        return 1;
    } else {
        NSUInteger frcSection = section - 1;
        id <NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController sections] objectAtIndex:frcSection];
        return [sectionInfo numberOfObjects];
    }
}

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];

    if (cell == nil) {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
    }

    [self configureCell:cell atIndexPath:indexPath];
    return cell;
}

- (void)configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath
{
    if (indexPath.section == 0) {
        cell.textLabel.text = entityOne.name;  //entityOne object passed from previous VC
    } else {
        entityTwo = [self.fetchedResultsController objectAtIndexPath:indexPath];
        cell.textLabel.text = entityTwo.name;
    }
}

- (void)controller:(NSFetchedResultsController *)controller
  didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
           atIndex:(NSUInteger)sectionIndex
     forChangeType:(NSFetchedResultsChangeType)type
{
    NSUInteger frcSectionIndex = 0;
    frcSectionIndex = sectionIndex + 1;

    switch(type) {
        case NSFetchedResultsChangeInsert:
            [self.tableView insertSections:[NSIndexSet indexSetWithIndex:frcSectionIndex] withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeDelete:
            [self.tableView deleteSections:[NSIndexSet indexSetWithIndex:frcSectionIndex] withRowAnimation:UITableViewRowAnimationFade];
            break;
    }
}

- (void)controller:(NSFetchedResultsController *)controller
   didChangeObject:(id)anObject
       atIndexPath:(NSIndexPath *)indexPath
     forChangeType:(NSFetchedResultsChangeType)type
      newIndexPath:(NSIndexPath *)newIndexPath
{
    UITableView *tableView = self.tableView;

    switch(type) {
        case NSFetchedResultsChangeInsert:
            [tableView insertRowsAtIndexPaths:@[newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeDelete:
            [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeUpdate:
            [self configureCell:[tableView cellForRowAtIndexPath:indexPath] atIndexPath:indexPath];
            break;

        case NSFetchedResultsChangeMove:
            [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationFade];
            [tableView insertRowsAtIndexPaths:@[newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
            break;
    }
}
4

1 回答 1

2

原因是获取结果控制器 (FRC) 只有一个部分 ( section #0 )，您希望将其显示在表格视图的第二部分 ( section #1 ) 中。

这是可能的，但您必须在 FRC 部分编号和表格视图部分编号之间进行映射，例如

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    if (section == 0) {
        return 1;
    } else {
        NSUInteger frcSection = section - 1;
        id <NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController sections] objectAtIndex:frcSection];
        return [sectionInfo numberOfObjects];
    }
}

中需要相同的映射cellForRowAtIndexPath。

在 FRC 委托方法didChangeObject中，didChangeSection您必须在调用表视图方法之前将节号加 1insertRowsAtIndexPaths （例如）。

添加： configureCell应该是这样的：

- (void)configureCell:(UITableViewCell *)cell atIndexPath:(NSIndexPath *)indexPath
{
    if (indexPath.section == 0) {
        cell.textLabel.text = entityOne.name;  //entityOne object passed from previous VC
    } else {
        NSIndexPath *frcIndexPath = [NSIndexPath indexPathForRow:indexPath.row inSection:(indexPath.section - 1)];
        entityTwo = [self.fetchedResultsController objectAtIndexPath:frcIndexPath];
        cell.textLabel.text = entityTwo.name;
    }
}

像这样didChangeObject：

- (void)controller:(NSFetchedResultsController *)controller
   didChangeObject:(id)anObject
       atIndexPath:(NSIndexPath *)indexPath
     forChangeType:(NSFetchedResultsChangeType)type
      newIndexPath:(NSIndexPath *)newIndexPath
{
    UITableView *tableView = self.tableView;
    NSIndexPath *tvIndexPath = [NSIndexPath indexPathForRow:indexPath.row inSection:(indexPath.section + 1)];
    NSIndexPath *tvNewIndexPath = [NSIndexPath indexPathForRow:newIndexPath.row inSection:(newIndexPath.section + 1)];

    switch(type) {
        case NSFetchedResultsChangeInsert:
            [tableView insertRowsAtIndexPaths:@[tvNewIndexPath] withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeDelete:
            [tableView deleteRowsAtIndexPaths:@[tvIndexPath] withRowAnimation:UITableViewRowAnimationFade];
            break;

        case NSFetchedResultsChangeUpdate:
            [self configureCell:[tableView cellForRowAtIndexPath:tvIndexPath] atIndexPath:tvIndexPath];
            break;

        case NSFetchedResultsChangeMove:
            [tableView deleteRowsAtIndexPaths:@[tvIndexPath] withRowAnimation:UITableViewRowAnimationFade];
            [tableView insertRowsAtIndexPaths:@[tvNewIndexPath] withRowAnimation:UITableViewRowAnimationFade];
            break;
    }
}

你可能明白了：

  • 当从 FRC 索引路径转到表视图索引路径时，向该部分添加一个。
  • 从表视图索引路径到 FRC 索引路径时，从该部分中减去一个。
于 2013-01-13T06:32:33.393 回答