swift - UITableView 不显示原型(prototype)单元格

Question

我正在尝试制作一个连接到 chromecast 以在电视上播放视频的应用程序，直到现在我仍在尝试使用两个 View Controller 显示视频链接，一个包含一个让用户获取视频页面的 WebView ，另一种是显示从第一个 View 推断出的所有视频链接，让用户从页面中选择要转换的视频。我能够获取链接，但问题是它不想显示在表格 View 单元格中。我尝试了很多方法，但我注意到，出于某种原因，根本没有调用 UITableViewDataSource 方法。这是代码:

ViewController.swift:

import UIKit

class ViewController: UIViewController, UIWebViewDelegate {
    //MARK: Outlets
    @IBOutlet weak var searchBar: UITextField!
    @IBOutlet weak var webView: UIWebView!
    @IBOutlet weak var cancelButton: UIButton!
    @IBOutlet weak var searchBarTrailingConstraint: NSLayoutConstraint!

    //MARK: Properties
    static var videoURLs: [String] = []

    //MARK: Methods
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        cancelButton.layer.cornerRadius = 5
        cancelButton.isHidden = true
        webView.delegate = self

    }

    func webViewDidFinishLoad(_ webView: UIWebView) {
        var videoTag = ""
        var embedTag = ""
        let htmlCode = webView.stringByEvaluatingJavaScript(from: "document.documentElement.outerHTML")
        let htmlTags = htmlCode!.components(separatedBy: "\n") as [String]
        for tag in htmlTags{
            var videoURL = ""
            if tag.contains("<video") {
                videoTag = tag.substring(from: tag.range(of: "<video")!.lowerBound)
                videoTag = videoTag.substring(to: (videoTag.range(of: ">")?.upperBound)!)
                if videoTag.contains("src"){
                    videoTag = tag.substring(from: tag.range(of: "src")!.upperBound)
                    for x in videoTag.characters{
                        if x == "\""{
                            continue
                        }else if x == "="{
                            continue
                        }else if x == ">"{
                            break
                        }else{
                            videoURL.append(x)
                        }
                    }
                }
                ViewController.videoURLs.append(videoURL)
            }
            if tag.contains("<embed") {
                embedTag = tag.substring(from: tag.range(of: "<embed")!.lowerBound)
                embedTag = embedTag.substring(to: (embedTag.range(of: ">")?.upperBound)!)
                if embedTag.contains("src"){
                    embedTag = tag.substring(from: tag.range(of: "src")!.upperBound)
                    for x in embedTag.characters{
                        if x == "\""{
                            continue
                        }else if x == "="{
                            continue
                        }else if x == ">"{
                            break
                        }else{
                            videoURL.append(x)
                        }
                    }
                }
                ViewController.videoURLs.append(videoURL)
            }
        }
        NotificationCenter.default.post(Notification(name: Notification.Name(rawValue: "Done")))
    }

    //MARK: Actions
    @IBAction func cancelPressed() {
        cancelButton.isHidden = true
        searchBarTrailingConstraint.constant = 0.0
        UIView.animate(withDuration: 0.25) {
            self.view.layoutIfNeeded()
        }
        searchBar.resignFirstResponder()
    }

    @IBAction func searchBarPressed() {
        searchBarTrailingConstraint.constant = (cancelButton.frame.width + 8.0) * -1
        UIView.animate(withDuration: 0.25) {
            self.view.layoutIfNeeded()
        }
        cancelButton.isHidden = false
    }

    @IBAction func returnButtonPressed(_ sender: UITextField) {
        cancelPressed()
        if let url = URL(string: sender.text!){
            if UIApplication.shared.canOpenURL(url){
                let request = URLRequest(url: url)
                webView.loadRequest(request)
            }else{
                let googleSearchURL = URL(string: "https://www.google.com/search?client=safari&q=\(url)&ie=UTF-8&oe=UTF-8")
                let request = URLRequest(url: googleSearchURL!)
                webView.loadRequest(request)
            }
        }else{
            var searchString: [String] = []
            var searchWord = ""
            for x in (sender.text?.characters)!{
                if x == " "{
                    searchString.append(searchWord)
                    searchWord = ""
                }else{
                    searchWord.append(x)
                }
            }
            //For appending the last word not followed by a space
            if !(searchString.last == searchWord){
                searchString.append(searchWord)
            }
            var googleSearchURL = "https://www.google.com/search?client=safari&ie=UTF-8&oe=UTF-8&q="
            for element in searchString{
                googleSearchURL.append(element)
                if !(searchString.last == element){
                    googleSearchURL.append("+")
                }

            }
            let request = URLRequest(url: URL(string:googleSearchURL)!)
            webView.loadRequest(request)
        }
    }

    @IBAction func backButtonPressed(_ sender: UIButton) {
        if webView.canGoBack{
            webView.goBack()
        }
    }

    @IBAction func forwardButtonPressed(_ sender: UIButton) {
        if webView.canGoForward {
            webView.goForward()
        }
    }

}

媒体 TableView Controller :

import UIKit
import AVFoundation

class MediaTableViewController: UIViewController, UITableViewDataSource {

    var videoURLs: [String] = []
    var videoScreenshots: UIImage!

    @IBOutlet weak var tableView: UITableView!

    override func viewDidLoad() {
        super.viewDidLoad()

        NotificationCenter.default.addObserver(self, selector: #selector(MediaTableViewController.replyToNotification), name: nil, object: nil)

        self.tableView.dataSource = self

    }

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

    func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        print("NOW!\n\n\n", indexPath.count)

        let cell = tableView.dequeueReusableCell(withIdentifier: "cell") as! MediaTableViewCell

        cell.videoImage.image = videoScreenshot(url: videoURLs[indexPath.count])
        cell.videoURL.text = videoURLs[indexPath.count]

        return cell
    }

    @objc func replyToNotification(){
        videoURLs = ViewController.videoURLs
        ViewController.videoURLs = []
    }

    // MARK: - Table view data source

    func videoScreenshot(url: String) -> UIImage? {

        let asset = AVURLAsset(url: URL(string: url)!)
        let generator = AVAssetImageGenerator(asset: asset)
        generator.appliesPreferredTrackTransform = true

        do {
            let imageRef = try generator.copyCGImage(at: CMTime(value: asset.duration.value/2, timescale: asset.duration.timescale), actualTime: nil)
            return UIImage(cgImage: imageRef)
        }
        catch let error as NSError
        {
            print("Image generation failed with error \(error)")
            return nil
        }
    }

}

MediaTableViewCell.swift:

import UIKit

class MediaTableViewCell: UITableViewCell {

    @IBOutlet weak var videoImage: UIImageView!
    @IBOutlet weak var videoURL: UITextView!

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

}

这是 Main.storyboard:

Answer 1

您没有调用 reloadData() 因此 tableView 处于空闲状态。

要解决此问题，请将以下内容添加到 MediaTableViewController:

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)
    tableView.reloadData()
}