通过searchBar过滤NSFetchedResultController而不加载基本暂停？

问题描述

我尝试在大型核心数据库（3.2万个对象）中创建搜索，但是当我向 UISearchBar 添加一些文本时，我会有些滞后（因为我的数据库正在更新使用新的搜索谓词）如何解决此问题？我该如何在后台线程中更新我的库？

i try to create search in big Core Data base (32 thousand objects) but when i added some text to the UISearchBar i have some lags (because my base is updating with new search Predicate) how to fix this? how can i update my base in background thread?

fetchedResultController代码

fetchedResultController code

    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作为搜索方法

and add some child MOC for searching methods

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

用于连接fetchedResultController

for connecting fetchedResultController I use

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)
        }
    })
}

搜索谓词使用以下代码更新

search Predicates are updated with following code

    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)
        }
    })

我有权使用searchMOC.perform并通过DispatchQueue更新tableView吗？
我在核心数据实体中用于谓词的所有属性均已索引，但添加搜索文本后我仍然有很多滞后性

Am I right to use searchMOC.perform and update the tableView via DispatchQueue?All my attributes which I use for Predicates in my Core Data Entity are "indexed", but I still have a lot of lags when added the search text

推荐答案

您必须在子上下文中获取，而不是在主上下文中获取结果控制器。在FRC中执行的任何操作都在主线程上，但是您需要进行后台搜索。

You have to fetch in the child context, not the main context fetched results controller. Whatever you do in the FRC is on the main thread, but you want a background search.

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