swift - Main.storyboard/Controller 和 searchBar 中的问题接线委托

Question

今天遇到一个问题。我在TodoListViewController.swift中编写代码，但searchBar.gelegate = self没有任何效果。还尝试将委托连接到Main.storyboard，但没有任何效果。这是TodoListViewController.swift代码：

import UIKit
import CoreData

class TodoListViewController: UITableViewController {
    
    @IBOutlet weak var searchBar: UISearchBar!
    
    var itemArray = [Item]()
    let dataFilePath = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)
    let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        // In Main.storyboard was set-up searchBar.delegate = self
        
        searchBar.delegate = self
        print(dataFilePath)
        loadItems()
    }
    
    //MARK: - Tableview Datasource Methods
    
    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return itemArray.count
    }
    
    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "ToDoItemCell", for: indexPath)
        
        let item = itemArray[indexPath.row]
        
        cell.textLabel?.text = item.title
        //Then sets cell of indexPath text = lists value of index path
        
        //Ternary operator =>
        // value = condifition ? valueTrue : valueFalse
        cell.accessoryType = item.done ? .checkmark : .none
        
        
        return cell
    }
    
    // when we click on cell
    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        
        itemArray[indexPath.row].done = !itemArray[indexPath.row].done
        
        saveItems()
        
        tableView.deselectRow(at: indexPath, animated: true)
    }
    
    //MARK: - Add New Items
    @IBAction func addButtonPressed(_ sender: UIBarButtonItem) {
        var textField = UITextField()
        let alert = UIAlertController(title: "Add New Todoey Item", message: "", preferredStyle: .alert)
        
        let action = UIAlertAction(title: "Add Item", style: .default) { (action) in
            // what will happen once the user clicks the Add Item button on our UIAlert.
            
            // handle an optional string that will never be nil (here). Handle value textField.text! below.
            
            if textField.text == "" {
                textField.placeholder = "Please enter text"
                self.present(alert, animated: true, completion: nil)
            } else {
                let newItem = Item(context: self.context)
                newItem.title = textField.text!
                newItem.done = false
                self.itemArray.append(newItem)
                
                self.saveItems()
            }
        }
        
        alert.addTextField { (alertTextField) in
            alertTextField.placeholder = "Create new item"
            textField = alertTextField
        }
        
        alert.addAction(action)
        
        // adding cancel action.
        let cancelAction = UIAlertAction(title: "Cancel", style: .cancel, handler: nil)

        alert.addAction(cancelAction)
        
        // to make the Add Item button bold and not Cancel Action.
        alert.preferredAction = action
        
        present(alert, animated: true, completion: nil)
    }
    
    //MARK: - Model Manipulations Method
    
    func saveItems() {
        do {
            try context.save()
        } catch {
            print("Error saving context \(error)")
        }
        self.tableView.reloadData()
    }
    
    func loadItems() {
        let request : NSFetchRequest<Item> = Item.fetchRequest()
        do {
            itemArray = try context.fetch(request)
        } catch {
            print("Error fetching data context \(error)")
        }
        self.tableView.reloadData()
    }
}

//MARK: - Search Bar Methods

extension TodoListViewController: UISearchBarDelegate {
    
    func searchBar(searchBar: UISearchBar, textDidChange searchText: String) {
            print("searchText \(searchText)")
        }
    
    func searchBarSearchButtonClicked(_ searchBar: UISearchBar) {
        let request : NSFetchRequest<Item> = Item.fetchRequest()
        print("Print: \(searchBar.text!)")
    }
}

这里AppDelegate.swift：

//
//  AppDelegate.swift
//  Destini
//
//  Created by Philipp Muellauer on 01/09/2015.
//  Copyright (c) 2015 London App Brewery. All rights reserved.
//

import UIKit
import CoreData

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {

    var window: UIWindow?


    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        return true
    }

    func applicationWillTerminate(_ application: UIApplication) {
        self.saveContext()
    }

    // MARK: - Core Data stack

    lazy var persistentContainer: NSPersistentContainer = {
        let container = NSPersistentContainer(name: "DataModel")
        container.loadPersistentStores(completionHandler: { (storeDescription, error) in
            if let error = error as NSError? {
                fatalError("Unresolved error \(error), \(error.userInfo)")
            }
        })
        return container
    }()

    // MARK: - Core Data Saving support

    func saveContext () {
        let context = persistentContainer.viewContext
        if context.hasChanges {
            do {
                try context.save()
            } catch {
                let nserror = error as NSError
                fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
            }
        }
    }

}

最终，当在应用程序中执行搜索时，应该触发到控制台的输出，这不会发生。不是输出到控制台，而是切换键盘大小写，字母变为大写。我将不胜感激您的帮助、建议和批评！:)

标签： swiftxcodedelegatesuisearchbar