Question

我正在尝试创建一个表视图，该表视图使用接收来自用户输入的textFields显示在另一个视图控制器中生成的数据，然后使用Core Data保存这些输入，然后将它们加载到tableView单元格中，除非它们不完全不会加载到单元格上。

我真的很困，我不知道该怎么尝试

这是第一个包含tableView的VC

    import UIKit
    import CoreData

let appDelegate = UIApplication.shared.delegate as? AppDelegate

class FriendsVC: UIViewController, UITableViewDelegate, UITableViewDataSource {

    @IBOutlet weak var tableView: UITableView!

    var friends : [Friend] = []


    override func viewDidLoad() {
        super.viewDidLoad()
        tableView.reloadData()
        tableView.delegate = self
        tableView.dataSource = self
    }
    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        self.tableView.reloadData()
        if friends.count >= 1{
            let endIndex = IndexPath(row: friends.count - 1, section: 0)
            tableView.scrollToRow(at: endIndex, at: .bottom, animated: false)
        }
    }
    @IBAction func addFriendsButtonWasPressed(_ sender: Any) {
        performSegue(withIdentifier: "toCreateFriends", sender: self)
    }


    func fetchCoreDataObjects(){
        self.fetch { (complete) in
            if complete{
                if friends.count >= 1 {
                    tableView.isHidden = false
                }else {
                    tableView.isHidden = true
                }
            }
        }
    }
    func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

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

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        guard let cell = tableView.dequeueReusableCell(withIdentifier: "FC") as? FriendCell  else{
            return UITableViewCell()
    }
        let friend = friends[indexPath.row]
        cell.configureCell(friend: friend)
        return cell
    }
    func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
        return true
    }
    func tableView(_ tableView: UITableView, editingStyleForRowAt indexPath: IndexPath) -> UITableViewCell.EditingStyle {
        return .none
    }
    func tableView(_ tableView: UITableView, editActionsForRowAt indexPath: IndexPath) -> [UITableViewRowAction]? {
        let deleteAction = UITableViewRowAction(style: .destructive, title: "Delete") { (rowAction , indexPath) in
            self.removeFriend(atIndexPat: indexPath)
            self.fetchCoreDataObjects()
            tableView.deleteRows(at: [indexPath], with: .automatic)

        }

        deleteAction.backgroundColor = #colorLiteral(red: 0.8078431487, green: 0.02745098062, blue: 0.3333333433, alpha: 1)
        return [deleteAction]
    }
}
extension FriendsVC {

    func fetch(completion : (_ complete : Bool)->()){
        guard let managedContext = appDelegate?.persistentContainer.viewContext else{return}
        let fetchRequest = NSFetchRequest<Friend>(entityName: "Friend")
        do{
            friends = try managedContext.fetch(fetchRequest)
            completion(true)
        } catch{
            debugPrint("Couldn't fetch\(error.localizedDescription)")
            completion(false)
        }
}

    func removeFriend(atIndexPat indexPath: IndexPath){
        guard let managedContext = appDelegate?.persistentContainer.viewContext else {return}
        managedContext.delete(friends[indexPath.row])
        do {
            try managedContext.save()
        } catch{
            debugPrint("Couldn't remove\(error.localizedDescription)")
        }

    }
}

-------------------------------------------------- -------------------------这是用户应在其中创建新朋友数据的另一个VC

    import UIKit
import CoreData

class CreateFriendsVC: UIViewController, UITableViewDelegate {

    @IBOutlet weak var nameLbl: UITextField!
    @IBOutlet weak var ageLbl: UITextField!
    @IBOutlet weak var genderLbl: UITextField!
    @IBOutlet weak var createBtn: UIButton!

    override func viewDidLoad() {
        super.viewDidLoad()
        createBtn.bindToKeyboard()
        let tap = UITapGestureRecognizer(target: self, action: #selector(CreateFriendsVC.handleTap))
        let pan = UIPanGestureRecognizer(target: self, action: #selector(CreateFriendsVC.handleTap))
        view.addGestureRecognizer(tap)
        view.addGestureRecognizer(pan)

    }
    @objc func handleTap(){
        view.endEditing(true)
    }

    @IBAction func createBtnPressed(_ sender: Any) {
        if nameLbl.text != "" && ageLbl.text != "" && genderLbl.text != "" {
            self.save { (complete) in
                if complete{
                    dismiss(animated: true, completion: nil)

                }
            }
        }

        dismiss(animated: true, completion: nil)
    }

    func save(completion : (_ finished : Bool)->()){
        guard let managedContext = appDelegate?.persistentContainer.viewContext else{return}
        let friend = Friend(context: managedContext)
        friend.age = ageLbl.text!
        friend.gender = genderLbl.text!
        friend.name = nameLbl.text!
        do{
            try managedContext.save()
            completion(true)
            print("Save success")
            print(friend.age!)
        } catch{
            debugPrint("Couldn't Save: \(error.localizedDescription)")
            completion(false)
        }
    }

}

================================================ =========================这是自定义单元格生成器

    import UIKit

class FriendCell: UITableViewCell {
    @IBOutlet weak var nameTxtLbl: UILabel!
    @IBOutlet weak var ageTxtLbl: UILabel!
    @IBOutlet weak var genderTxtLbl: UILabel!

    override func awakeFromNib() {
        super.awakeFromNib()
        // Initialization code
    }

    func configureCell(friend : Friend){
        self.nameTxtLbl.text = friend.name
        self.ageTxtLbl.text = friend.age
        self.genderTxtLbl.text = friend.gender

    }

}

预期结果应该是一个表格视图，其中包含显示所有用户输入数据的单元格。实际结果是一个空的表格视图单元格

Answer 1

在重新加载之前，您需要在fetchCoreDataObjects()中执行viewWillAppear

 override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)
    fetchCoreDataObjects()
    self.tableView.reloadData()
    if friends.count >= 1{
        let endIndex = IndexPath(row: friends.count - 1, section: 0)
        tableView.scrollToRow(at: endIndex, at: .bottom, animated: false)
    }
}

Answer 2

您永远不会调用fetchCoreDataObjects（）。在ViewDidLoad（）或ViewWillApear（）中调用此函数。

并更改如下代码。

var friends : [Friend] = [] {
    didSet {
        self.tableView.reloadData()
        if friends.count >= 1{
            let endIndex = IndexPath(row: friends.count - 1, section: 0)
            tableView.scrollToRow(at: endIndex, at: .bottom, animated: false)
        }
    }
}

tableViewCell不更新数据，因为它仅显示空白

2 个答案: