ios - 带有部分名称的 NSFetchedResultsController

Question

设想:

我有一个费用跟踪 iOS 应用程序，我将费用从费用详细 View Controller 存储到 TableView (带有获取的结果 Controller )中，该 TableView 显示费用列表以及类别、金额和日期。我的实体“Money”中确实有一个日期属性，它是支出或收入的父实体。

我的问题:

我想要的是基本上对给定一周、一个月或一年的费用/收入进行分类，并将其显示为部分标题标题，例如:(2012 年 10 月 1 日至 10 月 7 日)，它显示费用/收入金额和相关根据那一周的东西。该 View 中提供了两个按钮，如果我按下右侧按钮，它将一周增加一周(2012 年 10 月 1 日至 10 月 7 日现在显示 2012 年 10 月 8 日至 10 月 15 日)，同样，左侧按钮将减少一周一个星期。我在 View 中也有两个段控件。我想要做的是按下显示“每周”的段控制，如果我按下另一个显示“类别”的段 - 我将如何根据类别过滤掉我每周的费用/收入？

我想在我的表格 View 中显示两个部分(一个显示费用日期，另一个显示格式的收入日期(2012 年 10 月 1 日 - 2012 年 10 月 7 日))。我将如何实现这一目标？我写了一些伪代码，如果有人能告诉我如何完成上述操作，那就太好了。

编辑 - 获取 Controller

- (void)userDidSelectStartDate:(NSDate *)startDate andEndDate:(NSDate *)endDate
{    
    AppDelegate * applicationDelegate = (AppDelegate *) [[UIApplication sharedApplication] delegate];
    NSManagedObjectContext * context = [applicationDelegate managedObjectContext];

    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    // Edit the entity name as appropriate.
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Money" inManagedObjectContext:context];
    [fetchRequest setEntity:entity];

    [NSFetchedResultsController deleteCacheWithName:nil];

    //Here you create the predicate that filters the results to only show the ones with the selected date
    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(date >= %@) AND (date <= %@)", startDate, endDate];
    [fetchRequest setPredicate:predicate];

    // Set the batch size to a suitable number.
     [fetchRequest setFetchBatchSize:20];

    // Edit the sort key as appropriate.

    NSSortDescriptor * sortDescriptor1 = [[NSSortDescriptor alloc] initWithKey:@"type" ascending:YES];

    NSSortDescriptor *sortDescriptor2 = [[NSSortDescriptor alloc] initWithKey:@"date" ascending:YES];

    NSSortDescriptor *sortDescriptor3 = [[NSSortDescriptor alloc] initWithKey:@"cat" ascending:YES];

    NSArray * descriptors = [NSArray arrayWithObjects:sortDescriptor1, sortDescriptor2, sortDescriptor3, nil];

    [fetchRequest setSortDescriptors:descriptors];
    [fetchRequest setIncludesSubentities:YES];
    [fetchRequest setResultType:NSManagedObjectResultType];

    if(_fetchedResultsController)
    {
          [_fetchedResultsController release]; _fetchedResultsController = nil;

    }
    // Edit the section name key path and cache name if appropriate.
    // nil for section name key path means "no sections".
    _fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:context sectionNameKeyPath:@"type" cacheName:nil];

    _fetchedResultsController.delegate = self;

    NSError *anyError = nil;

    if(![_fetchedResultsController performFetch:&anyError])
    {
        NSLog(@"error fetching:%@", anyError);
    }

    [sortDescriptor1 release];
    [sortDescriptor2 release];
    [sortDescriptor3 release];

    [fetchRequest release];

     //Finally you tell the tableView to reload it's data, it will then ask your NEW FRC for the new data
    [self.dashBoardTblView reloadData];

}

编辑 - 获取 Controller 委托(delegate)方法

- (void)controllerWillChangeContent:(NSFetchedResultsController*)controller
{
     [self.dashBoardTblView beginUpdates];

}


- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
       atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type {

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

    case NSFetchedResultsChangeDelete:
        [self.dashBoardTblView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex]
                      withRowAnimation:UITableViewRowAnimationFade];
        break;
   }
}

- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath{

    switch(type) {
    case NSFetchedResultsChangeInsert:

        [self.dashBoardTblView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
        break;

    case NSFetchedResultsChangeDelete:

        [self.dashBoardTblView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
        break;

    case NSFetchedResultsChangeMove:

        [self.dashBoardTblView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
                         withRowAnimation:UITableViewRowAnimationFade];
        [self.dashBoardTblView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]
                         withRowAnimation:UITableViewRowAnimationFade];


        break;

    case NSFetchedResultsChangeUpdate:
    {
        [self.dashBoardTblView reloadRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
        break;
    }
  }
}

- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller
{
    [self.dashBoardTblView endUpdates];
} 

Answer 1

要将“费用”/“收入”对象分组到不同的部分，您需要添加 type Money 的属性实体，例如 Integer 0 的属性费用和1为收入。

要按类型(费用/收入)对 TableView 部分进行排序，请使用 type作为第一排序描述符:

NSSortDescriptor *s1 = [[NSSortDescriptor alloc] initWithKey:@"type" ascending:YES];

要按日期对每个部分中的条目进行排序，请使用 date作为第二个排序描述符:

NSSortDescriptor *s2 = [[NSSortDescriptor alloc] initWithKey:@"date" ascending:YES];

NSArray *descriptors = [NSArray arrayWithObjects:s1, s2, nil];
[fetchRequest setSortDescriptors:descriptors];

最后，要将表格 View 按类别分组，请使用 type如 sectionNameKeyPath :

NSFetchedResultsController *aFetchedResultsController =
   [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest
                                       managedObjectContext:context
                                         sectionNameKeyPath:type
                                                  cacheName:nil];

这应该给出 2 个部分，第一部分包含所有费用，第二部分包含所有收入。

现在对于部分标题，您必须实现 tableView:viewForHeaderInSection: (我希望我做对了):

- (UIView *)tableView:(UITableView *)tableView viewForHeaderInSection:(NSInteger)section
{
    id <NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController sections] objectAtIndex:section];
    Money *money = [[sectionInfo objects] objectAtIndex:0]; // The first object in this section
    NSNumber *type = money.type;
    if (type.intValue == 0) {
        // Create and return header view for "expense" section.

    } else {
        // Create and return header view for "incomes" section.

    }
}