ios - NSFetchedResultController 按日期排序部分得到重新排列

Question

我对 NSFetchedResultController 有疑问。我有一个按钮可以将两个值保存到核心数据:actualDate 和 shortDate。 actualDate 是一个 NSDate 变量(例如 2014-12-04 08:35:59 +0000)，而 shortDate 是一个字符串，通过 NSDateFormatter 从 actualDate 创建(例如 12 月 4 日)。

此按钮下方是一个应显示所有条目的 tableView，按日期降序排列，shortDate 作为每一天的部分名称(例如，12 月 4 日)。这在运行应用程序时适用于我当前的代码。

当我关闭应用程序并重新启动时出现问题。条目的顺序仍然正确，但部分名称已重新排列，例如，11 月 30 日显示在 12 月 4 日之前。我真的不知道问题是什么或如何解决。

感谢任何帮助!

这是我的 NSFetchedResultController 代码:

// MARK: - Fetched results controller

var fetchedResultsController: NSFetchedResultsController {
    if _fetchedResultsController != nil {

        return _fetchedResultsController!
    }

    let fetchRequest = NSFetchRequest()
    // Edit the entity name as appropriate.
    let entity = NSEntityDescription.entityForName("List", inManagedObjectContext: self.managedObjectContext!)
    fetchRequest.entity = entity

    // Set the batch size to a suitable number.
    fetchRequest.fetchBatchSize = 20

    // Edit the sort key as appropriate.
    let sortDescriptor = NSSortDescriptor(key: "actualDate", ascending: false)
    let sortDescriptor2 = NSSortDescriptor(key: "shortDate", ascending: false)

    fetchRequest.sortDescriptors = [sortDescriptor, sortDescriptor2]


    // Edit the section name key path and cache name if appropriate.
    // nil for section name key path means "no sections".
    let aFetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: self.managedObjectContext!, sectionNameKeyPath: "shortDate", cacheName: nil)
    aFetchedResultsController.delegate = self
    _fetchedResultsController = aFetchedResultsController

    var error: NSError? = nil
    if !_fetchedResultsController!.performFetch(&error) {
        // Replace this implementation with code to handle the error appropriately.
        // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
        //println("Unresolved error \(error), \(error.userInfo)")
        abort()
    }

    return _fetchedResultsController!
}
var _fetchedResultsController: NSFetchedResultsController? = nil

func controllerWillChangeContent(controller: NSFetchedResultsController) {
    self.tableView.beginUpdates()
}

func controller(controller: NSFetchedResultsController, didChangeSection sectionInfo: NSFetchedResultsSectionInfo, atIndex sectionIndex: Int, forChangeType type: NSFetchedResultsChangeType) {
    switch type {
    case .Insert:
        self.tableView.insertSections(NSIndexSet(index: sectionIndex), withRowAnimation: .Fade)
    case .Delete:
        self.tableView.deleteSections(NSIndexSet(index: sectionIndex), withRowAnimation: .Fade)
    default:
        return
    }
}

func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?) {
    switch type {
    case .Insert:
        tableView.insertRowsAtIndexPaths([newIndexPath!], withRowAnimation: .Fade)
    case .Delete:
        tableView.deleteRowsAtIndexPaths([indexPath!], withRowAnimation: .Fade)
 /*   case .Update:
        self.configureCell(tableView.cellForRowAtIndexPath(indexPath!)!, atIndexPath: indexPath!)*/
    case .Move:
        tableView.deleteRowsAtIndexPaths([indexPath!], withRowAnimation: .Fade)
        tableView.insertRowsAtIndexPaths([newIndexPath!], withRowAnimation: .Fade)
    default:
        return
    }
}

func controllerDidChangeContent(controller: NSFetchedResultsController) {
    self.tableView.endUpdates()
}

Answer 1

我知道这是一个老问题，但我遇到了同样的问题，我设法通过设置 cacheName 而不是让它 nil 来解决这个问题。

我为面临同样问题的每个人回答了这个老问题。