Ios 在UITableView上实现UISearchController，在swift 5中显示核心数据

我有一个核心数据Swift主/详细视图应用程序（代码位于），其中核心数据对象（称为sweetnote）基本上如下所示：

class sweetnote: NSObject {

private(set) var noteId        : UUID
private(set) var noteTitle     : String
private(set) var noteText      : NSAttributedString
private(set) var noteCreated   : Int64
private(set) var noteModified  : Int64
private(set) var noteCategory  : String

}

我有一个主视图控制器，它借助Helpers/sweetnoteCoreDataHelper.swift中名为readNotesFromCoreData的函数在UITableView中呈现这些注释：

static func readNotesFromCoreData(fromManagedObjectContext: NSManagedObjectContext) -> [sweetnote] {

    var returnedNotes = [sweetnote]()
    
    let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Note")
    fetchRequest.predicate = nil
    
    do {
        let fetchedNotesFromCoreData = try fromManagedObjectContext.fetch(fetchRequest)
        fetchedNotesFromCoreData.forEach { (fetchRequestResult) in
            let noteManagedObjectRead = fetchRequestResult as! NSManagedObject
            returnedNotes.append(sweetnote.init(
                noteId:        noteManagedObjectRead.value(forKey: "noteId")        as! UUID,
                noteTitle:     noteManagedObjectRead.value(forKey: "noteTitle")     as! String,
                noteText:      noteManagedObjectRead.value(forKey: "noteText")      as! NSAttributedString,
                noteCreated:   noteManagedObjectRead.value(forKey: "noteCreated")   as! Int64,
                noteModified:  noteManagedObjectRead.value(forKey: "noteModified")  as! Int64,
                noteCategory:  noteManagedObjectRead.value(forKey: "noteCategory")
                    as! String))
        }
    } catch let error as NSError {
        // TODO error handling
        print("Could not read notes from core data. \(error), \(error.userInfo)")
    }
    
    // Set note count
    self.count = returnedNotes.count
    
    // Sort by modified date
    return returnedNotes.sorted() {
        $0.noteModified > $1.noteModified
    }
}

static func readNotesFromCoreData（fromManagedObjectContext:NSManagedObjectContext）->[sweetnote]{
var returnedNotes=[sweetnote]（）
let fetchRequest=NSFetchRequest（entityName:“Note”）
fetchRequest.predicate=nil
做{
let fetchedNotesFromCoreData=try fromManagedObjectContext.fetch（fetchRequest）
fetchedNotesFromCoreData.forEach{（fetchRequestResult）位于
让noteManagedObjectRead=fetchRequestResult为！NSManagedObject
returnedNotes.append（sweetnote.init(
noteId:noteManagedObjectRead.value（forKey:“noteId”）作为！UUID，
noteTitle:noteManagedObjectRead.value（forKey:“noteTitle”）作为！字符串，
noteText:noteManagedObjectRead.value（forKey:“noteText”）作为！NSAttributedString，
noteCreated:noteManagedObjectRead.value（forKey:“noteCreated”）为！Int64，
noteModified:noteManagedObjectRead.value（forKey:“noteModified”）为！Int64，
noteCategory:noteManagedObjectRead.value（forKey：“noteCategory”）
as！字符串）
}
}将let错误捕获为NSError{
//TODO错误处理
打印（“无法从核心数据中读取注释。\（错误），\（错误.用户信息）”）
}
//设置纸币计数
self.count=returnedNotes.count
//按修改日期排序
return returnedNotes.sorted（）{
$0.noteModified>$1.noteModified
}
}

然后在我的主视图控制器（位于UI/MasterViewController.swift）中，我在UITableView的顶部配置了一个UISearchController，该控制器当前未应用任何基于文本的过滤逻辑，并且我无法确定需要更新的位置：

import UIKit
import Foundation
import CoreData

class MasterViewController: UITableViewController, NSFetchedResultsControllerDelegate, UISearchBarDelegate, UISearchResultsUpdating {

var detailViewController: DetailViewController? = nil
var searchtemplate: String? {didSet {print (searchtemplate as Any)}}

// Search results controller
let resultSearchController = UISearchController(searchResultsController: nil)
var sweetnotes: [sweetnote] = []
var searchResults: [sweetnote] = []


override func viewDidLoad() {
    super.viewDidLoad()

    // Core data initialization
    guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {
        // Create alert controller
        let alert = UIAlertController(
            title: "Could note get app delegate",
            message: "Could note get app delegate, unexpected error occurred. Try again later.",
            preferredStyle: .alert)

        // Add OK action
        alert.addAction(UIAlertAction(title: "OK",
                                      style: .default))
        // Show alert
        self.present(alert, animated: true)
        return
    }
    
    // Pass the context forward from the app delegate
    let managedContext = appDelegate.persistentContainer.viewContext
    
    // Set context in the storage
    sweetnoteStorage.storage.setManagedContext(managedObjectContext: managedContext)
    
    // Set the search controller programmatically
    resultSearchController.searchResultsUpdater = self
    resultSearchController.hidesNavigationBarDuringPresentation = false
    resultSearchController.obscuresBackgroundDuringPresentation = false
    self.definesPresentationContext = true
    // Scope bar
    //resultSearchController.searchBar.scopeButtonTitles = ["All", "Ideas", "Information", "Lifestyle", "Lists", "Recipes", "Other"]
    //searchView.addSubview(resultSearchController.searchBar)
    tableView.tableHeaderView = resultSearchController.searchBar
    resultSearchController.searchBar.tintColor = UIColor.darkGray
    resultSearchController.searchBar.barTintColor = UIColor(red: 0.9, green: 0.9, blue: 0.9, alpha: 0.8)
    resultSearchController.searchBar.placeholder = "Search sweetnotes"
    
    // Prefer large titles
    self.navigationController?.navigationBar.prefersLargeTitles = true
    
    // Edit-note button
    navigationItem.leftBarButtonItem = editButtonItem

    // Add-note button
    let addButton = UIBarButtonItem(barButtonSystemItem: .add, target: self, action: #selector(insertNewObject(_:)))
    navigationItem.rightBarButtonItem = addButton
    if let split = splitViewController {
        let controllers = split.viewControllers
        detailViewController = (controllers[controllers.count-1] as! UINavigationController).topViewController as? DetailViewController
    }
    self.tableView.delegate = self
}

...

override func viewWillAppear(_ animated: Bool) {
    clearsSelectionOnViewWillAppear = splitViewController!.isCollapsed
    super.viewWillAppear(animated)
}

// Dismiss search bar on scroll-down
override func viewWillDisappear(_ animated: Bool) {
    super.viewWillDisappear(animated)
    resultSearchController.dismiss(animated: false, completion: nil)
}

@objc
func insertNewObject(_ sender: Any) {
    performSegue(withIdentifier: "showCreateNoteSegue", sender: self)
}

// MARK: - Segues
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "showDetail" {
        if let indexPath = tableView.indexPathForSelectedRow {
            //let object = objects[indexPath.row]
            let object = sweetnoteStorage.storage.readNote(at: indexPath.row)
            let controller = (segue.destination as! UINavigationController).topViewController as! DetailViewController
            controller.detailItem = object
            controller.navigationItem.leftBarButtonItem = splitViewController?.displayModeButtonItem
            controller.navigationItem.leftItemsSupplementBackButton = true
            //controller.detailItem = resultSearchController.isActive ? searchResults[indexPath.row] : sweetnotes[indexPath.row]
        }
    }
}

// MARK: - Table View

func searchBar(_ searchBar: UISearchBar, selectedScopeButtonIndexDidChange selectedScope: Int) {
    filterContentForSearchText(searchBar.text!, scope: searchBar.scopeButtonTitles![selectedScope])
}

func updateSearchResults(for searchController: UISearchController) {
    guard let text = searchController.searchBar.text else { return }
        print(text)
}

func filterContentForSearchText(_ searchText: String, scope: String = "All") {
    searchtemplate = searchText
    tableView.reloadData()
}

func updateSearchResultsForSearchController(searchController: UISearchController, fromManagedObjectContext: NSManagedObjectContext) {
    let searchText = searchController.searchBar.text!
    let predicate = NSPredicate(format: "%K CONTAINS[c] %@", argumentArray: ["noteText", searchText])
    let fetchRequest = NSFetchRequest<NSFetchRequestResult>(entityName: "Note")
    fetchRequest.predicate = predicate
    
    do {
        let fetchedNotesFromCoreData = try fromManagedObjectContext.fetch(fetchRequest)
        fetchedNotesFromCoreData.forEach { (fetchRequestResult) in
            let noteManagedObjectRead = fetchRequestResult as! NSManagedObject
            searchResults.append(sweetnote.init(
                noteId:        noteManagedObjectRead.value(forKey: "noteId")        as! UUID,
                noteTitle:     noteManagedObjectRead.value(forKey: "noteTitle")     as! String,
                noteText:      noteManagedObjectRead.value(forKey: "noteText")      as! NSAttributedString,
                noteCreated:   noteManagedObjectRead.value(forKey: "noteCreated")   as! Int64,
                noteModified:  noteManagedObjectRead.value(forKey: "noteModified")  as! Int64,
                noteCategory:  noteManagedObjectRead.value(forKey: "noteCategory")
                    as! String))
        }
    } catch let error as NSError {
        // TODO error handling
        print("Could not read notes from core data. \(error), \(error.userInfo)")
    }
        tableView.reloadData()
}

...

override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        if resultSearchController.isActive && resultSearchController.searchBar.text != "" {
            return searchResults.count
        } else {
            return sweetnoteStorage.storage.count()
        }
    }

override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as! sweetnoteUITableViewCell
    
    //let note = fetchedResultsController.object(at: indexPath)
        //configureCell(cell, withEvent: note)
    if let object = sweetnoteStorage.storage.readNote(at: indexPath.row) {
        cell.noteTitleLabel!.text = object.noteTitle
        cell.noteTextLabel!.attributedText = object.noteText
        cell.noteCategoryLabel!.text = object.noteCategory
        cell.noteDateLabel!.text = sweetnoteDateHelper.convertDate(date: Date.init(minutes: object.noteModified))
    }
    
    //cell.contentView.layer.cornerRadius = 6.0
    //cell.contentView.layer.borderColor = UIColor.gray.withAlphaComponent(0.5).cgColor
    //cell.contentView.layer.borderWidth = 1.0
    //cell.contentView.layer.masksToBounds = true
    //cell.contentView.clipsToBounds = true
    
    cell.backgroundColor = UIColor.white
    cell.selectionStyle = UITableViewCell.SelectionStyle.none
    return cell
}

override func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
    // Return false if you do not want the specified item to be editable
    if resultSearchController.isActive {
        return false
    } else {
        return true
    }
}

override func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
    if editingStyle == .delete {
        presentDeletionFailsafe(indexPath: indexPath)
        //objects.remove(at: indexPath.row)
        //sweetnoteStorage.storage.removeNote(at: indexPath.row)
        //tableView.deleteRows(at: [indexPath], with: .fade)
    } else if editingStyle == .insert {
        // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view.
    }
}

// Deletion failsafe function
func presentDeletionFailsafe(indexPath: IndexPath) {
    let alert = UIAlertController(title: nil, message: "Are you sure you would like to delete this note?", preferredStyle: .alert)

    // Delete the note
    let yesAction = UIAlertAction(title: "Yes", style: .default) { _ in
        // replace data variable with your own data array
        sweetnoteStorage.storage.removeNote(at: indexPath.row)
        self.tableView.deleteRows(at: [indexPath], with: .fade)
    }

    alert.addAction(yesAction)

    // Cancel and don't delete note
    alert.addAction(UIAlertAction(title: "Cancel", style: .cancel, handler: nil))
    present(alert, animated: true, completion: nil)
}

func configureCell(_ cell: sweetnoteUITableViewCell, withEvent note: Note) {
    cell.noteTitleLabel!.text = note.noteTitle
    cell.noteTextLabel!.attributedText = note.noteText
    cell.noteCategoryLabel!.text = note.noteCategory
    cell.noteDateLabel!.text = sweetnoteDateHelper.convertDate(date: Date.init(minutes: note.noteModified))
}

}

导入UIKit
进口基金会
导入CoreData
类MasterViewController:UITableViewController、NSFetchedResultsControllerDelegate、UISearchBarDelegate、UISearchResultsUpdated{
var detailViewController:detailViewController？=nil
var searchtemplate:String？{didSet{print（searchtemplate如有）}
//搜索结果控制器
让resultSearchController=UISearchController（SearchResultController:nil）
变量sweetnotes:[sweetnote]=[]
var searchResults:[sweetnote]=[]
重写func viewDidLoad（）{
super.viewDidLoad（）
//核心数据初始化
让appDelegate=UIApplication.shared.delegate作为？appDelegate else{
//创建警报控制器
let alert=UIAlertController(
标题：“可以获取应用程序代理”，
消息：“无法获取应用程序委派，出现意外错误。请稍后重试。”，
preferredStyle:。警报）
//添加OK操作
alert.addAction（UIAlertAction）（标题：“确定”，
样式：。默认值）
//显示警惕
self.present（警报、动画：true）
返回
}
//从应用程序委托向前传递上下文
让managedContext=appDelegate.persistentContainer.viewContext
//在存储器中设置上下文
sweetnoteStorage.storage.setManagedContext（managedObjectContext:managedContext）
//以编程方式设置搜索控制器
resultSearchController.SearchResultsUpdate=self
resultSearchController.hidesNavigationBarDuringPresentation=false
resultSearchController.ObsuresBackgroundDuringPresentation=false
self.definesPresentationContext=true
//范围栏
//resultSearchController.searchBar.ScopeButtonTiles=[“所有”、“想法”、“信息”、“生活方式”、“列表”、“食谱”、“其他”]
//searchView.addSubview（resultSearchController.searchBar）
tableView.tableHeaderView=resultSearchController.searchBar
resultSearchController.searchBar.tintColor=UIColor.darkGray
resultSearchController.searchBar.barTintColor=UIColor（红色：0.9，绿色：0.9，蓝色：0.9，alpha:0.8）
resultSearchController.searchBar.placeholder=“搜索甜点”
//喜欢大标题
self.navigationController？.navigationBar.prefersLargeTitles=true
//编辑注释按钮
navigationItem.leftBarButtonItem=editButtonItem
//添加注释按钮
让addButton=UIBarButtonItem（barButtonSystemItem:.add，目标：self，action:#选择器（insertNewObject（：））
navigationItem.rightBarButtonItem=addButton
如果let split=splitViewController{
let controllers=split.viewControllers
detailViewController=（控制器[controllers.count-1]为！UINavigationController）。topViewController为？detailViewController
}
self.tableView.delegate=self
}
...
覆盖函数视图将出现（uo动画：Bool）{
清除SelectionInviewMillAppear=splitViewController！。已合并
超级。视图将显示（动画）
}
//在向下滚动时关闭搜索栏
覆盖函数视图将消失（u动画：Bool）{
超级。视图将消失（动画）
resultSearchController.Disclose（动画：false，完成：nil）
}
@objc
func insertNewObject（\发送方：任意）{
PerformScheue（标识符为“showCreateNoteSegue”，发送者：self）
}
//马克：赛格
覆盖功能准备（对于segue:UIStoryboardSegue，发送方：有吗？）{
如果segue.identifier==“showDetail”{
如果让indexPath=tableView.indexPathForSelectedRow{
//let object=objects[indexPath.row]
让对象=sweetnoteStorage.storage.readNote（位于：indexPath.row）
让控制器=（segue.destination为！UINavigationController）。topViewController为！DetailViewController
controller.detailItem=对象