为什么在我保存数据数据并调用 tableview.reloadData() 函数后我的 tabe 视图不会重新加载

Question

I am confused to why my table view is not reloading after i call the tableView.reloadData() function. Here is what you should know about my project. The initial view controller is a tableViewController and when you click the add button in the navigation bar it pulls up presents the "addItemViewController". It is presented overCurrentContext. Everything to this point works fine, but the part that doesn't work is when you fill out the info in the pop up I created and push the button to save it it saves to the core data fill but when i reload it it doesnt even call that. When i close the app and reload it the data shows up but it doesnt show up when i add it and call the same function.

import UIKit
import CoreData
protocol reloadTableView: class {
    func reloadTableView()
}
class TableViewController: UITableViewController {
    
    //Global Variables
    let addItemVC = AddItemController()
    var itemArray = [Item]()
    let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
    
    override func viewDidLoad() {
        super.viewDidLoad()
        addItemVC.delegate = self
        loadItems()
    }

    // MARK: - Table view data source
    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: Constants.cellIdentifier, for: indexPath) as! Cell
        let array = itemArray[indexPath.row]
        cell.dateCreated.text = array.dateCreated
        cell.workoutLabel.text = array.workoutName
        cell.weightLifted.text = array.weight
        return cell
    }

//MARK: - Add Button Pressed
    @IBAction func addItemPressed(_ sender: UIBarButtonItem) {
        let storyboard = UIStoryboard(name: "AddItem", bundle: nil)
        let addItemVC = storyboard.instantiateViewController(identifier: "AddItemController")
        addItemVC.isModalInPresentation = true
        addItemVC.modalPresentationStyle = .overCurrentContext
        addItemVC.modalTransitionStyle = .crossDissolve
        addItemVC.navigationController?.isNavigationBarHidden = true
        present(addItemVC, animated: true, completion: nil)
    }
    
    
    
    
    
    
//MARK: - Create and Load Functions
    func saveData() {
        do {
            try context.save()
        } catch {
            print("Error Saving Data \(error)")
        }
        tableView.reloadData()
    }
    func loadItems() {
        let request: NSFetchRequest<Item> = Item.fetchRequest()
           do {
           itemArray = try context.fetch(request)
           } catch {
               print("error")
           }
        tableView.reloadData()
    }
}

//MARK:// - Add Item Vc Delegate
extension TableViewController: reloadTableView {
    func reloadTableView() {
        do {
            try context.save()
        } catch {
            print("Error Saving Data \(error)")
        }
        let request: NSFetchRequest<Item> = Item.fetchRequest()
           do {
           itemArray = try context.fetch(request)
           } catch {
               print("error")
        }
        tableView.reloadData()
        print("There are", itemArray.count, "in the item array")
        print(itemArray.last?.workoutName)
          //the print statement are not showing up in console
    }
}

and the second file

import UIKit
import CoreData

class AddItemController: UIViewController {
    
    let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
    var delegate: reloadTableView?
    
    @IBOutlet weak var viewContainer: UIView!
    @IBOutlet weak var exercise: UITextField!
    @IBOutlet weak var weight: UITextField!
    @IBOutlet weak var reps: UITextField!
    
    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
    @IBAction func addMaxPressed(_ sender: UIButton) {
        if exercise.text != "" &&  weight.text != "" &&  reps.text != "" {
            let newItem = Item(context: context)
            let formatter = DateFormatter()
            newItem.dateCreated = formatter.formattedDate()
            newItem.weight = weight.text
            newItem.reps = reps.text
            newItem.workoutName = exercise.text
            dismiss(animated: true) {
                self.delegate?.reloadTableView()
            }
        }
    }
    @IBAction func exitPressed(_ sender: UIButton) {
        dismiss(animated: true, completion: nil)
    }
}

//MARK: - UITextField func
extension AddItemController: UITextFieldDelegate {
    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        self.view.endEditing(true)
        return true
    }
}

Answer 1

You're setting the delegate on the wrong instance of the add item view controller. You create one instance with...

let addItemVC = AddItemController()

...and another with...

let addItemVC = storyboard.instantiateViewController(identifier: "AddItemController")

You set the delegate on the first of those, but present the second. That means when you get to...

self.delegate?.reloadTableView()

...of the presented controller, nothing happens.

If you're not using the first instance, get rid of it and set the delegate in the same section where you set the presentation style, etc.

When you put ? after an optional, it means you don't want to know whether it did what you asked or not. Obviously, you do want to know so you should test the value instead and print a message if the value isn't what you expect.