在UITableView的顶部实现UISearchController，以快速显示5

如何解决在UITableView的顶部实现UISearchController，以快速显示5

我有一个核心数据Swift主/详细视图应用程序（代码位于here），其中的核心数据对象称为sweetnote，基本上是这样的：

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Master视图控制器，该控件借助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
    }
}

然后在主视图控制器（位于UI / MasterViewController.swift中）中，我在UITableView的顶部配置了一个UISearchController，该控件当前未基于文本应用任何过滤逻辑，并且我无法确定在哪里需要更新：

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,\(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))
}

}

函数updateSearchResultsForSearchController是我尝试建立谓词并执行搜索结果获取请求的地方，基于那里的一些类似问题，人们在核心数据项目之上实现了搜索控制器，但我肯定仍然缺少某些东西因为将文字输入搜索栏时，所有注释仍保留在表格视图中。

由于我在此上花了很多时间，所以任何答案/建议都将受到高度赞赏。如果可以帮助您，我很乐意提供更多信息和上下文。同样，代码位于项目here的“ searchbar”分支中。预先非常感谢。