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)
}

在添加数据时，不会调用FetchResultControllerDataProvider中的任何方法。但我无法弄清楚原因。

有人可以帮我这个吗？

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()
    }
}

因此调用了这部分代码，并且没有抛出错误但我试图检查核心数据sql文件，它似乎是空的。所以没有添加数据。

Answer 1

您需要检查委托和fetchedResultsController对象是否仍处于活动状态，并在添加数据时正确填充。你能尝试打印这些变量的值吗？

self.fetchedResultController

self.fetchedResultController.delegate

添加数据时是否会在PersistentStore中插入数据？

Answer 2

    NSFetchRequest *fetchRequest11 = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity1 = [NSEntityDescription entityForName:@"RemainderDataBase" inManagedObjectContext:[self managedObjectContext]];
    [fetchRequest11 setEntity:entity1];
    NSPredicate *p1=[NSPredicate predicateWithFormat:@"startdate < %@", [NSDate date]];
    [fetchRequest11 setPredicate:p1];
    NSError *fetchError;
    NSError *error;
    NSArray *fetchedProducts1=[managedObjectContext executeFetchRequest:fetchRequest11 error:&fetchError];
    for (NSManagedObject *product in fetchedProducts1)
    {
        [managedObjectContext deleteObject:product];
        [tableview reloadData];
    }
    [managedObjectContext save:&error];
    [self.tableview reloadData];


 self.FRC = [[NSFetchedResultsController alloc]initWithFetchRequest:fetchRequest managedObjectContext:[self managedObjectContext] sectionNameKeyPath:nil cacheName:nil];

    self.FRC.delegate = self;

    NSError *fetchingErr=nil;

    if ([self.FRC performFetch:&fetchingErr])
    {
        NSLog(@"Succesfully Fetched data from RemainderDataBase");
    }
    else
    {
        NSLog(@"Failed To Fetch data from RemainderDataBase");
    }

设置获取请求以检索数据

注意：正确设置代表..

在ViewDidLoad中添加这些行

id delegate = [[UIApplication sharedApplication] delegate];
    self.managedObjectContext = [delegate managedObjectContext];

不调用NSFetchedResultsControllerDelegate委托方法

2 个答案: