Swift-PrepareforSegue不工作[重复]

Question

我有三个数组来制作一个tableView和第二个ViewController。一个显示tableView上每个节的标题，一个显示标题，还有一个显示每个单元格的链接。当我构建并点击其中一个单元格时，我会得到：

致命错误：在展开可选值时意外发现nil

在这条线上：

 let url = URL(string: websiteURL)!

print("hello")

import UIKit




class FirstViewController: UIViewController, UITableViewDataSource, UITableViewDelegate {



var headers = ["Bein Sports", "Sky Sports", "Alkass", "Other"]

var channels = [["Bein Sports 1","Bein Sports 2","Bein Sports 3","Bein Sports 4","Bein Sports 5","Bein Sports 6","Bein Sports 7","Bein Sports 8","Bein Sports 9","Bein Sports 10","Bein Sports News"],
                          ["Sky Sports 1","Sky Sports 2","Sky Sports 3","Sky Sports 4","Sky Sports 5"],
                          ["Alkass One", "Alkass Two", "Alkass Three", "Alkass Four", "Alkass Five"],
                          ["BT Sports 1", "BT Sports 2", "Real Madrid TV", "Real Madrid TV 2"]]

var links = [["https://www.google.ca","https://www.facebook.com","https://facebook.com","https://facebook.com","https://facebook.com","https://facebook.com","https://facebook.com","https://facebook.com","https://facebook.com","https://facebook.com","https://facebook.com"],
             ["https://facebook.com","https://facebook.com","https://facebook.com","https://facebook.com","https://facebook.com"],
             ["https://facebook.com","https://facebook.com","https://facebook.com","https://facebook.com","https://facebook.com"],
             ["http://twitter.com","http://facebook.com","http://www.google.com","http://www.instagram.com"]]

var myIndex : IndexPath = IndexPath()

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
}

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

func numberOfSections(in tableView: UITableView) -> Int {
    return channels.count //Rows
}

func tableView(_ tableView: UITableView, titleForHeaderInSection section: Int) -> String? {
    return headers[section] //Sections
}

func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
    let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath)
    cell.textLabel?.text = channels[indexPath.section][indexPath.row] //TextLabel
    return cell
}

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
    myIndex = IndexPath(row: indexPath.section, section: indexPath.row)
    performSegue(withIdentifier: "segue", sender: self)
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

func prepareForSegue(segue: UIStoryboardSegue, sender: AnyObject?)
{
    if (segue.identifier == "segue") {
        let viewController = segue.destination as! ChannelViewController
        // Now you have a pointer to the child view controller.
        // You can save the reference to it, or pass data to it.
        viewController.websiteURL = links[myIndex.section][myIndex.row]
        print("google")
    }
}
}

下面是第二个视图控制器代码：

import UIKit
import WebKit
import AVKit
import AVFoundation

class ChannelViewController: UIViewController {


    var webView: WKWebView!
    var websiteURL = ""



override func viewDidLoad() {
    super.viewDidLoad()

    // Do any additional setup after loading the view.



    webView = WKWebView()
    webView.scrollView.isScrollEnabled = false


    view.addSubview(webView)
    let url = URL(string: websiteURL)!
    let req:URLRequest = URLRequest(url: url)
    webView.load(req)

    webView.translatesAutoresizingMaskIntoConstraints = false
    let width = NSLayoutConstraint(item: webView, attribute: .width, relatedBy: .equal, toItem: view, attribute: .width, multiplier: 1.0, constant: 0) //Constraints

    let height = NSLayoutConstraint(item: webView, attribute: .height, relatedBy: .equal, toItem: view, attribute: .height, multiplier: 1.0, constant: 0)
    view.addConstraints([width,height]) //Constraints

}


override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

Answer 1

您使用prepare for segue的方式是不正确的。

你应该使用

override func prepare(for segue: UIStoryboardSegue, sender: Any?) 

也叫它

self.performSegue(withIdentifier: "segue", sender: nil)