类别未显示在模拟器中...卡住了

Question

我正在尝试创建一个待办事项列表应用程序，以在每个类别中添加类别和项目。类别保存在领域数据库中，但根本没有加载。我像修改了我的代码，仍然没有任何显示。 tableview单元格是可单击的，但名称未显示在屏幕上。尽管它仍然保存在领域文件中。如果有人知道解决方案，请帮助我，这是代码。任何帮助表示赞赏

import UIKit
import RealmSwift
class CategoryViewController: UITableViewController {
    let realm = try! Realm()
    var categories: Results<Category>!
    override func viewDidLoad() {
        super.viewDidLoad()
        loadCategories()
    }

    @IBAction func addButtonPressed(_ sender: UIBarButtonItem) {
        var textfield = UITextField()
        let alert = UIAlertController(title: "Add new Category", message: "", preferredStyle: .alert)
        let action = UIAlertAction(title: "Add", style: .default) {
            (action) in
            let newCategory = Category()
            newCategory.name = textfield.text!
            self.save(category: newCategory)
        }
        alert.addAction(action)
        alert.addTextField {
            (field) in
            textfield = field
            textfield.placeholder = "Add new Category"
        }
        present(alert, animated: true, completion: nil)
    }

    //MARK: - TableView Delegate Methods
    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        performSegue(withIdentifier: "goToItems", sender: self)
    }

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
        let destinationVC = segue.destination as! ToDoListViewController
        if let indexPath = tableView.indexPathForSelectedRow {
            destinationVC.selectedCategory = categories[indexPath.row]
        }
    }

    //MARK: - TableView DataSource Methods
    override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return categories.count
    }

    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        let cell = tableView.dequeueReusableCell(withIdentifier: "CategoryCell", for: indexPath)
        let category = categories[indexPath.row]
        cell.textLabel?.text = category.name
        return cell
    }

    //MARK: - Data Manipulation Methods
    func save(category: Category) {
        do {
            try realm.write {
                realm.add(category)
            }
        }
        catch {
            print("Error saving category, \(error)")
        }
        self.tableView.reloadData()
    }

    func loadCategories() {
        categories = realm.objects(Category.self)
        tableView.reloadData()
    }

}

这些是Category和Item类：...

import Foundation
import RealmSwift

class Category: Object {
  dynamic var name: String = ""
  let items = List<Item>()
}

import Foundation
import RealmSwift

class Item: Object {
  dynamic var title: String = ""
  dynamic var done: Bool = false
  var parentCategory = LinkingObjects(fromType: Category.self, property: "items")
}

下图是应用程序的情况。

Answer 1

问题是您的领域对象。类别对象的定义如下：

class Category: Object {
  dynamic var name: String = ""
  let items = List<Item>()
}

它必须是这样，

class Category: Object {
  @objc dynamic var name: String = ""
  let items = List<Item>()
}

添加@objc将var标记为由Realm管理：

或这样

@objcMembers class Category: Object {
  dynamic var name: String = ""
  let items = List<Item>()
}

其中@objcMembers使所有由Realm管理的变量。]​​>