Swift UISearchController连接在Core Data Project中,app运行,但搜索不更新

Question

过去几天我一直在为TableViewController使用Core Data 的Swift项目创建一个过滤器而摔跤.我终于想通了我需要使用a UISearchController,创建一个NSPredicatefor searchController.searchBar等.

我发现这篇文章非常有帮助,但在我对TVC这个项目进行建模之后,我发现"所有的灯都亮着,但没有人在家".我可以搜索,创建谓词searchBar,添加,删除等,但单元格不会更新以进行搜索.我错过了什么,但我不知道是什么.

以下是我的代码的相关部分.

class MasterViewController: UITableViewController, NSFetchedResultsControllerDelegate, UISearchControllerDelegate, UISearchResultsUpdating

// Properties that get instantiated later

var detailViewController: DetailViewController? = nil
var addNoteViewController:AddNoteViewController? = nil  // I added this
var managedObjectContext: NSManagedObjectContext? = nil

// Added variable for UISearchController
var searchController: UISearchController!
var searchPredicate: NSPredicate? // I added this. It's optional on and gets set later

    override func viewDidLoad() {
        super.viewDidLoad()

        self.navigationItem.leftBarButtonItem = self.editButtonItem()

        if let split = self.splitViewController {
            let controllers = split.viewControllers
            let context = self.fetchedResultsController.managedObjectContext
            let entity = self.fetchedResultsController.fetchRequest.entity!
            self.detailViewController = controllers[controllers.count-1].topViewController as? DetailViewController
        }

        // UISearchController setup
        searchController = UISearchController(searchResultsController: nil)
        searchController.dimsBackgroundDuringPresentation = false
        searchController.searchResultsUpdater = self
        searchController.searchBar.sizeToFit()
        self.tableView.tableHeaderView = searchController?.searchBar
        self.tableView.delegate = self
        self.definesPresentationContext = true
    }

    // MARK: - UISearchResultsUpdating Delegate Method
    // Called when the search bar's text or scope has changed or when the search bar becomes first responder.
    func updateSearchResultsForSearchController(searchController: UISearchController) {
        let searchText = self.searchController?.searchBar.text // steve put breakpoint
        println(searchController.searchBar.text)
        if let searchText = searchText {
            searchPredicate = NSPredicate(format: "noteBody contains[c] %@", searchText)
            self.tableView.reloadData()
            println(searchPredicate)
        }
    }

    override func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {
        if editingStyle == .Delete {
            var note: Note
            if searchPredicate == nil {
                note = self.fetchedResultsController.objectAtIndexPath(indexPath) as! Note
            } else {
                let filteredObjects = self.fetchedResultsController.fetchedObjects?.filter() {
                    return self.searchPredicate!.evaluateWithObject($0)
                }
                note = filteredObjects![indexPath.row] as! Note
            }
            let context = self.fetchedResultsController.managedObjectContext
            context.deleteObject(note)

            var error: NSError? = nil
            if !context.save(&error) {
                abort()
            }
        }
    }

    // MARK: - Fetched results controller

    var fetchedResultsController: NSFetchedResultsController {
        if _fetchedResultsController != nil {
            return _fetchedResultsController!
        }

        let fetchRequest = NSFetchRequest()
        // Edit the entity name as appropriate.
        let entity = NSEntityDescription.entityForName("Note", inManagedObjectContext: self.managedObjectContext!)
        fetchRequest.entity = entity

        // Set the batch size to a suitable number.
        fetchRequest.fetchBatchSize = 20

        // Edit the sort key as appropriate.
        let sortDescriptor = NSSortDescriptor(key: "noteTitle", ascending: false)
        let sortDescriptors = [sortDescriptor]

        fetchRequest.sortDescriptors = [sortDescriptor]

        // Edit the section name key path and cache name if appropriate.
        // nil for section name key path means "no sections".
        let aFetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest, managedObjectContext: self.managedObjectContext!, sectionNameKeyPath: nil, cacheName: "Master")
        aFetchedResultsController.delegate = self
        _fetchedResultsController = aFetchedResultsController

        var error: NSError? = nil
        if !_fetchedResultsController!.performFetch(&error) {
            // Replace this implementation with code to handle the error appropriately.
            // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
            println("Unresolved error \(error), \(error?.userInfo)")
            abort()
        }

        return _fetchedResultsController!
    }

    var _fetchedResultsController: NSFetchedResultsController? = nil

    func controllerWillChangeContent(controller: NSFetchedResultsController) {
        //        self.tableView.beginUpdates() // ** original code, change if doesn't work** steve put breakpoint here
        // ANSWER said this section is redundant, but keeping it b/c it doesn't crash
        if searchPredicate == nil {
            tableView.beginUpdates()
        } else {
            (searchController.searchResultsUpdater as! MasterViewController).tableView.beginUpdates()
        }
    }

    func controller(controller: NSFetchedResultsController, didChangeSection sectionInfo: NSFetchedResultsSectionInfo, atIndex sectionIndex: Int, forChangeType type: NSFetchedResultsChangeType) {

        var tableView = UITableView()
        if searchPredicate == nil {
            tableView = self.tableView
        } else {
            tableView = (searchController.searchResultsUpdater as! MasterViewController).tableView
        }

        switch type {
        case .Insert:
            self.tableView.insertSections(NSIndexSet(index: sectionIndex), withRowAnimation: .Fade)
        case .Delete:
            self.tableView.deleteSections(NSIndexSet(index: sectionIndex), withRowAnimation: .Fade)
        default:
            return
        }
    }

我认为我的问题在这一部分"存在".自动填充功能一直是我的朋友,但我searchIndex在AutoComplete 中看不到" ".我想我错过了什么,但我不确定是什么或如何.

如果你已经做到这一点,感谢阅读.这是我正在研究的分支的GitHub回购.

    func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?) {

        var tableView = UITableView()

        if self.searchPredicate == nil {
            tableView = self.tableView
        } else {
            tableView = (self.searchController.searchResultsUpdater as! MasterViewController).tableView
        }

        switch type {
        case .Insert:
            println("*** NSFetchedResultsChangeInsert (object)")
            tableView.insertRowsAtIndexPaths([newIndexPath!], withRowAnimation: .Fade)
        case .Delete:
            println("*** NSFetchedResultsChangeDelete (object)")
            tableView.deleteRowsAtIndexPaths([indexPath!], withRowAnimation: .Fade)
        case .Update:
            println("*** NSFetchedResultsChangeUpdate (object)")
            // TODO: need fix this

            // ORIGINAL CODE
            // self.configureCell(tableView.cellForRowAtIndexPath(indexPath!)!, atIndexPath: indexPath!) // original code

            // PROSPECTIVE SOLUTION CODE
            println("*** NSFetchedResultsChangeUpdate (object)")
            if searchPredicate == nil {
                self.configureCell(tableView.cellForRowAtIndexPath(indexPath!)!, atIndexPath: indexPath!) // original code
            } else {
                // Should search the do something w/ the UISearchControllerDelegate or UISearchResultsUpdating
                // Instead of "indexPath", it should be "searchIndexPath"--How?
                let cell = tableView.cellForRowAtIndexPath(searchIndexPath) as LocationCell // My cell is a vanilla cell, not a xib
                let location = controller.objectAtIndexPath(searchIndexPath) as Location // My object is a "Note"
                cell.configureForLocation(location) // This is from the other guy's code, don't think it's applicable to me
            }

        case .Move:
            println("*** NSFetchedResultsChangeMove (object)")
            tableView.deleteRowsAtIndexPaths([indexPath!], withRowAnimation: .Fade)
            tableView.insertRowsAtIndexPaths([newIndexPath!], withRowAnimation: .Fade)
        default:
            return
        }
    }



    func controllerDidChangeContent(controller: NSFetchedResultsController) {
        if self.searchPredicate == nil {
            self.tableView.endUpdates()
        } else {
            println("controllerDidChangeContent")
            (self.searchController.searchResultsUpdater as! MasterViewController).tableView.endUpdates()
        }

    }

编辑:每个@pbasdf,我正在添加TableView方法.

// MARK: - Table View

override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
    return self.fetchedResultsController.sections?.count ?? 0
}

override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    if self.searchPredicate == nil {
        let sectionInfo = self.fetchedResultsController.sections![section] as! NSFetchedResultsSectionInfo
        return sectionInfo.numberOfObjects
    }

    let sectionInfo = self.fetchedResultsController.sections![section] as! NSFetchedResultsSectionInfo
    return sectionInfo.numberOfObjects
}

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as! UITableViewCell
    self.configureCell(cell, atIndexPath: indexPath)
    return cell
}

override func tableView(tableView: UITableView, canEditRowAtIndexPath indexPath: NSIndexPath) -> Bool {
    // Return false if you do not want the specified item to be editable.
    return true
}

Answer 1

问题在于您的tableView数据源的方法:numberOfSectionsInTableview:,tableView:numberOfRowsInSection:,和tableView:cellForRowAtIndexPath:.如果searchPredicate不是nil,那么你需要每个方法返回不同的结果 - 就像你的tableView:commitEditingStyle:方法一样.我会创建filteredObjects一个实例属性(在类的开头定义),以便所有这些方法都可以访问它:

var filteredObjects : [Note]? = nil

现在,当搜索文本更改时,您希望重建filteredObjects数组.因此updateSearchResultsForSearchController,添加一行以根据新谓词重新计算它:

    if let searchText = searchText {
        searchPredicate = NSPredicate(format: "noteBody contains[c] %@", searchText)
        filteredObjects = self.fetchedResultsController.fetchedObjects?.filter() {
            return self.searchPredicate!.evaluateWithObject($0)
        } as [Note]?
        self.tableView.reloadData()
        println(searchPredicate)
    }

我还建议(为简单起见),当您激活搜索时,结果会显示在一个部分中(否则您必须计算出过滤结果中有多少部分 - 可能但很烦人):

override func numberOfSectionsInTableView(tableView: UITableView) -> Int {
    if searchPredicate == nil {
        return self.fetchedResultsController.sections?.count ?? 0
    } else {
        return 1
    }
}

接下来,如果searchPredicate不是nil,则该节中的行数将是filteredObjects的计数:

override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
    if self.searchPredicate == nil {
        let sectionInfo = self.fetchedResultsController.sections![section] as! NSFetchedResultsSectionInfo
        return sectionInfo.numberOfObjects
    } else {
        return filteredObjects?.count ?? 0
    }
}

最后,如果searchPredicate不是nil,则需要使用filteredObjects数据构建单元格,而不是fetchedResultsController:

override func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCellWithIdentifier("Cell", forIndexPath: indexPath) as! UITableViewCell
    if searchPredicate == nil {
        self.configureCell(cell, atIndexPath: indexPath)
        return cell
    } else {
        // configure the cell based on filteredObjects data
        ...
        return cell
    }
}

不确定你的细胞中有哪些标签等,所以我留给你排序.