Question

我刚开始并已经组合了另一个List应用程序，因为那里没有足够的信息...但是我遇到了一个问题，即在输入新条目后没有调用reloadData（）为日记。如果我再次使用XCode重新编译应用程序，则新条目将出现在tableView上。

我已包含信号1 SIGTERM错误，该错误在重新编译应用程序时出现。

import Foundation
import UIKit
import CoreData


class TableViewController: UITableViewController {

    @IBAction func addNewItem(_ sender: Any) {
        return
    }

    @IBOutlet var entityTableView: UITableView!


    var items: [Entity] = [] //Should be same name as new Entity in the dataModel
    let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext


    //Calls the getData which will fetch the new entry and then reload the view
    //The register will linkt he UITableViewCell class with the tableView
    //estimatedRowHeight and rowHeight define the label size and I intentionally want text cut off (journal entries might be quite long) so a preview works
    override func viewDidLoad() {
        super.viewDidLoad()
        self.tableView.estimatedRowHeight = 60
        self.tableView.rowHeight = UITableView.automaticDimension
    }

    //Will reload the table every time that the view is shown to allow it to show the most recent entries
    override func viewWillAppear(_ animated: Bool) {
        getData()
        print ("\(items)")
        NSFetchRequest<NSManagedObject>(entityName: "entry")
    }

    //Func will get the data. Print to check that data has been pulled and then refreshes the
    func getData() {
        do {
            items = try context.fetch(Entity.fetchRequest())
            print (items)
            DispatchQueue.main.async {
                self.tableView.reloadData()
            }
        } catch {
            print("Unable to fetch the data")
        }
    }
}

extension TableViewController {

    //Will have the items presented as most recent on the top
    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as UITableViewCell

        cell.textLabel?.text = items.reversed()[indexPath.row].newEntry

        return cell
    }

    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return items.count
    }

    override func tableView(_ tableView: UITableView, trailingSwipeActionsConfigurationForRowAt indexPath: IndexPath) -> UISwipeActionsConfiguration? {
        let DeleteAction = UIContextualAction(style: .destructive, title: "Delete", handler: { (action, view, success) in
            print("Delete")
        })
        DeleteAction.backgroundColor = .red

        let item = self.items [indexPath.row]
        self.context.delete(item)
        (UIApplication.shared.delegate as! AppDelegate).saveContext()

        self.items.remove(at: indexPath.row)
        tableView.deleteRows(at: [indexPath], with: .fade)
        return UISwipeActionsConfiguration(actions: [DeleteAction])
    }
}

addNewEntry的viewController是：

import UIKit
import CoreData

class addNewEntryViewController: UIViewController, UITextViewDelegate {


    @IBOutlet weak var journalEntryField: UITextView!

    @IBAction func cancelEntry (_ sender: Any) {
        dismiss(animated: true, completion: nil)
    }

    @IBOutlet weak var headerForNewEntry: UILabel!

    @IBAction func saveNewEntry(_ sender: Any) {
       guard let enteredText = journalEntryField?.text else {
                 return
             }

             if enteredText.isEmpty ||  journalEntryField?.text == "Type anything..."{

             let alert = UIAlertController(title: "Please Type Something", message: "Your entry was left blank.", preferredStyle: .alert)
             alert.addAction(UIAlertAction(title: "Okay", style: .default) { action in

             })

             self.present(alert, animated: true, completion: nil)

         } else {

                 guard let entryText = journalEntryField?.text else {
                     return
                 }

                 let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
                 let newEntry =  Entity(context: context)
                newEntry.newEntry = entryText

                 (UIApplication.shared.delegate as! AppDelegate).saveContext()

                 dismiss(animated: true, completion: nil)
        }
    }

    //Will have the delegate set to the current view
    override func viewDidLoad() {
        super.viewDidLoad()
        journalEntryField.delegate = self
    }

    //Func will hide the keyboard after pressing the Return button
    func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool {
        if (text == "\n") {
            textView.resignFirstResponder()
            return false
        }
        return true
    }
}

[<Journal__Core_Data_.Entity: 0x600003423e80> (entity: Entity; id: 0xcae729498383650b <x-coredata://71565814-E7F1-4D16-852F-7D8CBEA199F2/Entity/p1>; data: <fault>), <Journal__Core_Data_.Entity: 0x600003427de0> (entity: Entity; id: 0xcae72949838f650b <x-coredata://71565814-E7F1-4D16-852F-7D8CBEA199F2/Entity/p2>; data: <fault>)] [<Journal__Core_Data_.Entity: 0x600003423e80> (entity: Entity; id: 0xcae729498383650b <x-coredata://71565814-E7F1-4D16-852F-7D8CBEA199F2/Entity/p1>; data: <fault>), <Journal__Core_Data_.Entity: 0x600003427de0> (entity: Entity; id: 0xcae72949838f650b <x-coredata://71565814-E7F1-4D16-852F-7D8CBEA199F2/Entity/p2>; data: <fault>)] 2019-12-18 14:56:25.896548+0800 Journal (Core Data)[12470:652660] [Warning] Warning once only: Detected a case where constraints ambiguously suggest a height of zero for a table view cell's content view. We're considering the collapse unintentional and using standard height instead. Cell: <Journal__Core_Data_.TableViewCell: 0x7fb367f6d8c0; baseClass = UITableViewCell; frame = (0 28; 414 99); text = 'Poop face'; clipsToBounds = YES; autoresize = W; layer = <CALayer: 0x600001769b00>>

Answer 1

在“ TableViewController”文件中替换var items: [Entity] = []

与此

var items: [Entity] = []{
        didSet{
            DispatchQueue.main.async {
                self.tableView.reloadData()
            }
        }
    }

这将在每个新条目上重新加载tableView。此后，您无需在Controller中的任何位置添加tableView.reloadData()。

日记-DispatchQueue-未调用self.tableView.reloadData（）

1 个答案: