从本地JSON（Radio Station应用程序）中提取URL

Question

所以我在我的应用程序中有4个电台，我从JSON电台获取最近播放的歌曲，但现在我的问题是我需要从当前播放的任何电台获取JSON网址。我有一个本地JSON，它提取从主viewController中选择的站的所有信息。这是我最近播放的歌曲viewController的代码。我认为我的代码是正确的，但只是遗漏了一些可能很小的东西。

 guard let urlText = URL(string: currentStation.longDesc)
                else { return }

上面的这行代码我不断收到错误：线程1：致命错误：在展开Optional值时意外发现nil （我在车站的LongDescription中有30个最近播放的曲目的JSON网址，这就是为什么它的currentStation.longDesc）

var currentStation: RadioStation!

上面的代码行告诉viewController当前正在播放哪个电台。

//----------
//MARK: JSON
//----------

//The Initial Response From The JSON
struct Response: Codable {

    var playHistory: Album

}

//The Album Received Which Is An Array Of Song Data
struct Album: Codable {
    var song: [SongData]

}

//The SongData From The PlayHistory Album
struct SongData: Codable{

    var album: String
    var artist: String
    var cover: String
    var duration: String
    var programStartTS: String
    var title: String
}


class TableViewController: UITableViewController {

    //1. Create An Array To Store The SongData
    var songs = [SongData]()
    var currentStation: RadioStation!

    override func viewDidLoad() { super.viewDidLoad()


        self.tableView.delegate = self
        self.tableView.dataSource = self

        //2. Load The JSON From The Main Bundle

        guard let urlText = URL(string: currentStation.longDesc)
            else { return }


        do{
            //a. Get The Data From The From The File
            let data = try Data(contentsOf: urlText)

            //b. Decode The Data To Our Structs
            let albumData = try JSONDecoder().decode(Response.self, from: data)

            //c. Append The Songs Array With The PlayHistory
            albumData.playHistory.song.forEach { songs.append($0) }

            //d. Test Some Data
            print("""
                **The First Album Details**
                Album = \(songs[0].album)
                Artist = \(songs[0].artist)
                Cover = \(songs[0].cover)
                Duration = \(songs[0].duration)
                Start = \(songs[0].programStartTS)
                Title = \(songs[0].title)
                """)

            //3. Load The Data
            DispatchQueue.main.async {
                self.tableView.reloadData()
            }
        }catch{

            print(error)
        }

    }

    //-----------------
    //MARK: UITableView
    //-----------------


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

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


    override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        //1. Create A Cell
        let cell = tableView.dequeueReusableCell(withIdentifier: "cell", for: indexPath) as! TableViewCell

        //2. Set It's Text
        cell.songTitle.text = songs[indexPath.row].title
        cell.artistLabel.text = songs[indexPath.row].artist

        //3. Get The Image
        if let imageURL = URL(string: songs[indexPath.row].cover){

            let request = URLSession.shared.dataTask(with: imageURL) { (imageData, response, error) in

                if let error = error{

                    print(error)

                }else{

                    guard let image = imageData else { return }

                    DispatchQueue.main.async {
                        cell.songCover.image = UIImage(data: image)
                        cell.setNeedsLayout()
                        cell.layoutIfNeeded()
                    }

                }
            }


            request.resume()
        }

        return cell

    }


    override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {

        print("""
            **Album \(indexPath.row) Selected**
            Album = \(songs[indexPath.row].album)
            Artist = \(songs[indexPath.row].artist)
            Cover = \(songs[indexPath.row].cover)
            Duration = \(songs[indexPath.row].duration)
            Start = \(songs[indexPath.row].programStartTS)
            Title = \(songs[indexPath.row].title)
            """)
    }

}