ios - 未调用 controllerDidChangeContent

Question

我的应用程序非常简单:一个 TableViewController 显示存储在 Core Data 中的内容。添加按钮以模态方式推送第二个 View ，这使我可以将内容保存到 Core Data 中。我正在使用 NSFetchedResultsController 来填充主 VC。如果我将内容保存到 Core Data 并再次显示主视图 Controller ，我的 tableView 不会刷新其数据。我认为这是因为未调用委托(delegate)方法。知道为什么吗？

import UIKit
import CoreData

class MainTableViewController: UITableViewController, NSFetchedResultsControllerDelegate {
var managedContext: NSManagedObjectContext!
var fetchedResultsController: NSFetchedResultsController!
lazy var coreDataStack = CoreDataStack()

    override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view, typically from a nib.
    self.setToolbarItems(toolBar().cons, animated: true)
    self.navigationController?.setToolbarHidden(false, animated: true)
    let fetchRequest = NSFetchRequest(entityName: "CDPodcast")
    let sort = NSSortDescriptor(key: "artist", ascending: true)
    fetchRequest.sortDescriptors = [sort]
    managedContext = coreDataStack.context
    fetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: managedContext, sectionNameKeyPath: nil, cacheName: nil)
    fetchedResultsController.delegate = self
    var error: NSError? = nil
    if (!fetchedResultsController.performFetch(&error)) {
        println("Error: \(error?.localizedDescription)")
    }

}

以下均未调用

 func controller(controller: NSFetchedResultsController, didChangeSection sectionInfo: NSFetchedResultsSectionInfo, atIndex sectionIndex: Int, forChangeType type: NSFetchedResultsChangeType) {
    println("change section")
}

func controllerWillChangeContent(controller: NSFetchedResultsController) {
    tableView.reloadData()
    println("begin updates")
}

func controllerDidChangeContent(controller: NSFetchedResultsController) {
    tableView.reloadData()
    println("end updates")
}

编辑:更多代码

 func saveToCoreData(name: String, artist: String, summary: String, feedURL: String, artworkURL: String, date: NSDate, episodes: [MWFeedItem]) {
    self.managedContext = coreDataStack.context
    let podcastEntity = NSEntityDescription.entityForName("CDPodcast", inManagedObjectContext: self.managedContext)
    currentPodcast = CDPodcast(entity: podcastEntity!, insertIntoManagedObjectContext: self.managedContext)
    currentPodcast.name = name
    currentPodcast.artist = artist
    currentPodcast.summary = summary
    currentPodcast.feedURL = feedURL
    currentPodcast.artworkURL = artworkURL
    currentPodcast.date = date


    let episodesEntity = NSEntityDescription.entityForName("CDEpisode", inManagedObjectContext: self.managedContext)
    for var i = 0; i < episodes.count; i++ {
        let episodesToSave = CDEpisode(entity: episodesEntity!, insertIntoManagedObjectContext: self.managedContext)
        var episode: AnyObject = currentPodcast.episode.mutableCopy() as! NSMutableOrderedSet

        println("There are \(episodes.count) items in the episodes array")
        episodesToSave.title = episodes[i].title
        episodesToSave.downloadURL = episodes[i].enclosures[0].valueForKey("url") as! String
        episodesToSave.showNotes = episodes[i].summary
        episode.addObject(episodesToSave)
        currentPodcast.episode = episode.copy() as! NSOrderedSet
    }


    self.coreDataStack.saveContext()

}

Answer 1

问题是我的 ManagedObjectContext 没有被正确传递。 println(context) 在 App Delegate 和 View Controller #3 之间返回了不同的内存地址。我没有找到解决此问题的正确方法，所以我只是在 View Controller 之间传递上下文。有正确的上下文修复它。