ios - NSFetchedResultsControllerDelegate 委托(delegate)方法未被调用

Question

这是我的代码:

class FetchResultControllerDataProvider: NSObject, NSFetchedResultsControllerDelegate {

    private let fetchedResultController: NSFetchedResultsController
    private var delegate: TodayViewController!

    init(fetchedResultController: NSFetchedResultsController, delegate: TodayViewController) {
        self.fetchedResultController = fetchedResultController
        self.delegate = delegate

        super.init()
        self.fetchedResultController.delegate = self
        try! self.fetchedResultController.performFetch()
    }

    func controllerWillChangeContent(controller: NSFetchedResultsController) {
        print("Controller will change")
    }

    func controllerDidChangeContent(controller: NSFetchedResultsController) {
        print("COntroller did changed")
    }

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

    func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?) {
        print("Controller did change object at indexpath")
    }
}


func loadData() {
    let request = NSFetchRequest(entityName: Transaction.entityName)
    request.predicate = Transaction.defaultPredicate
    request.sortDescriptors = []
    request.returnsObjectsAsFaults = false
    request.fetchBatchSize = 20

    let frc = NSFetchedResultsController(fetchRequest: request, managedObjectContext: context, sectionNameKeyPath: nil, cacheName: nil)
    let dataProvider = FetchResultControllerDataProvider(fetchedResultController: frc, delegate: self)
    dataSource = TableViewDataSource(tableView: self.tableView, dataProvider: dataProvider, delegate: self)
}

当我添加数据时，FetchResultControllerDataProvider 中的两个方法都没有被调用。但我不明白为什么。

有人可以帮我吗？

编辑:

添加数据:

func addTransaction() {
    self.context.performChanges {
        Transaction.insert(self.context, name: self.name.text!, amount: Double(self.amount.text!)!, type: self.currentTypeTag)
    }

public func saveOrRoleback() -> Bool {

    do {
        try save()
        return true
    } catch {
        rollback()
        return false
    }
}

public func performChanges(block: () -> ()) {

    performBlockAndWait {
        block()
        self.saveOrRoleback()
    }
}

所以调用了这部分代码，并没有抛出任何错误。
但是我试着查看核心数据的sql文件，好像是空的。所以没有添加数据。

Answer 1

添加数据时，您需要检查 delegate 和 fetchedResultsController 对象是否仍然存在并正确填充。您可以尝试打印这些变量的值吗？

self.fetchedResultController

self.fetchedResultController.delegate

当您添加数据时，数据是否被插入到您的 PersistentStore 中？