Question

我尝试在大型核心数据库中创建搜索（32,000个对象），但是当我向UISearchBar添加一些文本时，我有一些滞后（因为我的基础是用新的搜索谓词更新）如何解决这个问题？如何在后台线程中更新我的基础？

fetchedResultController代码

    lazy var context: NSManagedObjectContext = {
        let appDelegate = (UIApplication.shared.delegate as? AppDelegate)
        let context = appDelegate!.managedObjectContext
        return context//appDelegate!.managedObjectContext
    }()

    lazy var fetchedResultsController: NSFetchedResultsController<CardsBaseClass> = {
        let fetchRequest = NSFetchRequest<CardsBaseClass>(entityName: "CardsBase")
        let sortDescriptor = NSSortDescriptor(key: "cardName", ascending: true)
        fetchRequest.sortDescriptors = [sortDescriptor]

        fetchRequest.predicate = nil
        fetchRequest.fetchBatchSize = 50
        fetchRequest.returnsObjectsAsFaults = false

        //let mainContext = (UIApplication.shared.delegate as? AppDelegate)?.managedObjectContext

        let fetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: self.context, sectionNameKeyPath: nil, cacheName: nil)
        fetchedResultsController.delegate = self
        return fetchedResultsController
    }()

并添加一些子MOC以搜索方法

    lazy var searchMOC: NSManagedObjectContext = {
        let moc = NSManagedObjectContext(concurrencyType: .privateQueueConcurrencyType)
        moc.parent = self.context
        return moc
    }()

用于连接fetchedResultController我使用

override func viewDidAppear(_ animated: Bool) {
    self.view.gestureRecognizers?.removeAll()
    connectFetchedRequest()
}

func connectFetchedRequest() {
    indicatorLoad.startAnimating()
    context.perform({
        do {
            try self.fetchedResultsController.performFetch()
            DispatchQueue.main.async(execute: {
                self.tableView.reloadData()
                self.indicatorLoad.stopAnimating()
            })
        } catch {
            print(error)
        }
    })
}

搜索谓词更新时使用以下代码

    searchMOC.performAndWait({
        if searchText != "" {
            let predicate = NSPredicate(format: "\(self.searchPredicateName) contains[c] %@", searchText)
            predicateArray.append(predicate)
        }
        self.fetchedResultsController.fetchRequest.predicate = NSCompoundPredicate(andPredicateWithSubpredicates: predicateArray)
        do {
            try self.fetchedResultsController.performFetch()
            DispatchQueue.main.async(execute: {
                self.tableView.reloadData()
            })
        } catch {
            print(error)
        }
    })

我是否正确使用searchMOC.perform并通过DispatchQueue更新tableView？我在核心数据实体中用于Predicates的所有属性都被“编入索引”，但在添加搜索文本时仍然存在很多滞后

Answer 1

您必须获取子上下文，而不是主要上下文获取结果控制器。无论你在FRC中做什么都在主线程上，但你想要一个后台搜索。

通过searchBar过滤NSFetchedResultController而不加载基础暂停？

1 个答案: