当我尝试在它前面显示一个 uiview 时，tableview 向我发送了一个错误

Question

我是 Xcode 和 Swift 的新手，按照教程进行操作，当我在 tableview 前面调用 UIView 以便用户可以创建新内容时发现了一个问题

注意：我已经尝试过 link 显示的内容，但没有解决我的问题

我正在使用 Xcode 11.3.1 和 Swift

这是我的代码

渠道模型

import Foundation

struct Channel : Decodable {
    public private(set) var channelTitle: String!
    public private(set) var channelDescription: String!
    public private(set) var id: String!
}
Class ChannelCell

import UIKit

class ChannelCell: UITableViewCell {

    // Outlets
    @IBOutlet weak var channelName: UILabel!


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

    override func setSelected(_ selected: Bool, animated: Bool) {
        super.setSelected(selected, animated: animated)
        if selected {
            self.layer.backgroundColor = UIColor(white: 1, alpha: 0.2).cgColor
        } else {
            self.layer.backgroundColor = UIColor.clear.cgColor
        }
    }

    func configureCell(channel: Channel) {
        let title = channel.channelTitle ?? ""
        channelName.text = "#\(title)"
    }
}

频道视图控制器

import UIKit

class ChannelVC: UIViewController, UITableViewDelegate, UITableViewDataSource {

    // Outlets

    @IBOutlet weak var loginBtn: UIButton!
    @IBOutlet weak var userImg: CircleImage!
    @IBOutlet weak var tableView: UITableView!
    @IBAction func prepareForUnwind(segue: UIStoryboardSegue) {}

    override func viewDidLoad() {
        super.viewDidLoad()

        tableView.delegate = self <<<<<<<<< here I get the error message ***
Thread 1: Fatal error: Unexpectedly found nil while implicitly unwrapping an Optional value
        tableView.dataSource = self


        self.revealViewController()?.rearViewRevealWidth = self.view.frame.size.width - 60
        NotificationCenter.default.addObserver(self, selector: #selector(ChannelVC.userDataDidChange(_:)), name: NOTIF_USER_DATA_DID_CHANGE, object: nil)
    }

    override func viewDidAppear(_ animated: Bool) {
        setupUserInfo()
    }
When I pressed the add channel button comes the problem

    @IBAction func addChannelPressed(_ sender: Any) {
        if AuthService.instance.isLoggedIn {
            let addChannel = ChannelVC()
            addChannel.modalPresentationStyle = .custom
            present(addChannel, animated: true, completion: nil)
        } else {
            performSegue(withIdentifier: TO_LOGIN, sender: nil)
        }
    }

    @IBAction func loginBtnPressed(_ sender: Any) {
        if AuthService.instance.isLoggedIn {
            let profile = ProfileVC()
            profile.modalPresentationStyle = .custom
            present(profile, animated: true, completion: nil)
        } else {
           performSegue(withIdentifier: TO_LOGIN, sender: nil)
        }
    }

    @objc func userDataDidChange(_ notif: Notification) {
        setupUserInfo()
    }

    func setupUserInfo() {
        if AuthService.instance.isLoggedIn {
            loginBtn.setTitle(UserDataService.instance.name, for: .normal)
            userImg.image = UIImage(named: UserDataService.instance.avatarName)
            userImg.backgroundColor = UserDataService.instance.returnUIColor(components: UserDataService.instance.avatarColor)
        } else {
            loginBtn.setTitle("Login", for: .normal)
            userImg.image = UIImage(named: "menuProfileIcon")
            userImg.backgroundColor = UIColor.clear
        }
    }

    // Protocols for UITableViewDataSource
    // # of sections
    // # rows in the section
    // function to setup the cells

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        if let cell = tableView.dequeueReusableCell(withIdentifier: "channelCell", for: indexPath) as? ChannelCell {
I double check the reusable identifier is OK

            let channel = MessageService.instance.channels[indexPath.row]
            cell.configureCell(channel: channel)
            return cell
        } else {
            return UITableViewCell()
        }
    }

    func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }

    func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        if MessageService.instance.channels.count == 0 {
            tableView.setEmptyView(title: "Message!", message: "You don´t have any channel, create a new one")
        }
        return MessageService.instance.channels.count
    }
}

这是我点击 addChannel 函数时想要显示的视图 view to present

这是调试区 debug area

Answer 1

你犯了一个非常常见的错误。线

let addChannel = ChannelVC()

创建一个新的控制器实例，它不是故事板中的实例。因此插座没有连接，代码崩溃。

将其替换为（相应地调整标识符）

let storyboard = UIStoryboard(name: "Main", bundle: nil)
let addChannel = storyboard.instantiateViewController(withIdentifier: "ChannelVC") as! ChannelVC

或者创建一个segue。