Question

我遇到这个问题，我想从一个主列表移到它的子列表，例如，当我单击tableViewController中的面包店时，应该将我带到另一个具有相关食品（例如蛋糕，饼干等）的tableViewController。但是我无法从表格视图1传递到表格视图2。

我尝试使用segues，但是它不起作用。我尝试使用原型进行链接，但这也失败了，它不会切换到下一个表格视图导入UIKit 导入CoreData

ViewController类：UIViewController，UITableViewDelegate {

var name = "-1"
@IBOutlet weak var tableView: UITableView!
var list: [NSManagedObject] = []
override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view.
    title = "Lists"
    tableView.register(UITableViewCell.self, forCellReuseIdentifier: "Cell")
   // performSegue(withIdentifier: "show", sender: self)
}

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {
        return
    }

    let managedContext = appDelegate.persistentContainer.viewContext

    let fetchRequest = NSFetchRequest<NSManagedObject>(entityName: "List")

    do {
        list = try managedContext.fetch(fetchRequest)
    } catch let error as NSError {
        print("Could not fetch. \(error), \(error.userInfo)")
    }
}

@IBAction func addName(_ sender: Any) {

    let alert = UIAlertController(title: "New list", message: "Create a new list", preferredStyle: .alert)

    let saveAction = UIAlertAction(title: "Save", style: .default) {
        [unowned self] action in
        guard let textField = alert.textFields?.first,
            let nameToSave = textField.text else {
                return
        }

        self.save(name: nameToSave)
        self.tableView.reloadData()
    }

    let cancelAction = UIAlertAction(title: "Cancel", style: .cancel)
    alert.addTextField()
    alert.addAction(saveAction)
    alert.addAction(cancelAction)

    present(alert, animated: true)
}

func save(name: String) {
    guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {
        return
    }

    let managedContext = appDelegate.persistentContainer.viewContext

    let entity = NSEntityDescription.entity(forEntityName: "List", in: managedContext)!

    let listItem = NSManagedObject(entity: entity, insertInto: managedContext)

    listItem.setValue(name, forKeyPath: "name")

    do {
        try managedContext.save()
        list.append(listItem)
    } catch let error as NSError {
        print("Could not save. \(error), \(error.userInfo)")
    }
}

func delete(name: String) {
    guard let appDelegate = UIApplication.shared.delegate as? AppDelegate else {
        return
    }

    let managedContext = appDelegate.persistentContainer.viewContext

    let fetchRequest: NSFetchRequest<List> = List.fetchRequest()
    fetchRequest.predicate = NSPredicate(format: "name = %@", "\(name)")

    do {
        let objects = try managedContext.fetch(fetchRequest)
        for object in objects {
            managedContext.delete(object)
        }
        try managedContext.save()
    } catch let error as NSError {
        print("Could not save. \(error), \(error.userInfo)")
    }

    self.tableView.reloadData()
}

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    let listItem = list[indexPath.row]
    name = (listItem.value(forKey: "name") as? String)!
    self.performSegue(withIdentifier: "show", sender: self)
}

override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
    if segue.identifier == "show" {
        let dest = segue.destination as! SecondViewController
        dest.segName = name
    }
}

}

扩展ViewController：UITableViewDataSource { func tableView（_ tableView：UITableView，numberOfRowsInSection部分：Int）-> Int { 返回list.count }

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let listItem = list[indexPath.row]
    let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
    cell.textLabel?.text = listItem.value(forKeyPath: "name") as? String
    return cell
}

func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
    if editingStyle == .delete {
        let listItem = list[indexPath.row]
        let listItemName: String = listItem.value(forKey: "name") as? String ?? "-1"
        delete(name: listItemName)
    }
}

}

// 2nd表格视图控制器导入UIKit

SecondViewController类：UIViewController {

var segName = String()
override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.
}

将值从一个tableView Controller发送到另一个

0 个答案: