使用 swift 从本地 JSON 文件点击 table 视图中的按钮播放歌曲

Question

我有一个包含一些数据的本地 JSON 文件。需要知道如何从本地 JSON 加载音频并将其加载到 table 视图中的按钮。我的 JSON:

{
    "beatPack":
    {
        "loops": [
            {
                "name": "Away we go",
                "producer": "Tubular Kingz",
                "count": "28",
                "genre": "Lo-fi Hip Hop",
                "imagename": "beatpackone"
                "songName": "alien.mp3"
            }
        ]
    }
}

因此它应该将每首歌曲显示到 table 视图中的按钮。这是我的歌曲方法，它们可以在每一行中显示歌曲，但不是 JSON 并且不是我需要的正确编号：

func playLoop(songName: String) {
        let url = Bundle.main.url(forResource: songName, withExtension: ".mp3")  // you should check it for errors
        audioPlayer = try! AVAudioPlayer(contentsOf: url!)  // of course you should catch the error and deal with it...
        audioPlayer.play()
        print(songName)
    }
    
    func gettingSongName() {
        let folderURL = URL(fileURLWithPath: Bundle.main.resourcePath!)
        
        do {
            let songPath = try FileManager.default.contentsOfDirectory(at: folderURL, includingPropertiesForKeys: nil, options: .skipsHiddenFiles)
            
            for song in songPath {
                var mySong = song.absoluteString
                
                if mySong.contains(".mp3") {
                    let findString = mySong.components(separatedBy: "/")
                    mySong = findString[findString.count - 1]
                    mySong = mySong.replacingOccurrences(of: "%20", with: " ")
                    mySong = mySong.replacingOccurrences(of: ".mp3", with: "")
                    songs.append(mySong)
                }
            }
        } catch {
            
        }
    }

这是我的 table 观点：

extension BPLibraryViewController: UITableViewDataSource, UITableViewDelegate, UIScrollViewDelegate {
    
    func tableView(_ tableView: UITableView, heightForRowAt indexPath: IndexPath) -> CGFloat {
        return 180
    }
    
    func numberOfSections(in tableView: UITableView) -> Int {
        return 1
    }
    
    public func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return loopsName.count
    }
    
    public func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
        
        let cell = tableView.dequeueReusableCell(withIdentifier: S.newOneCell, for: indexPath) as! BeatPackLibraryCell
        
        let loopsCount = loopsName[indexPath.row]  //Instance of our arrays from JSON
        
        cell.loopNameLabel.text = loopsCount.name
        cell.producerNameLabel.text = loopsCount.producer
        cell.loopsCountLabel.text = String(loopsName.count)
        cell.genreLabel.text = loopsCount.genre
        cell.firstBeatButtonLabel.setImage(UIImage(named: loopsCount.imagename), for: .normal)
        
        cell.delegate = self
        cell.selectionStyle = .none
        cell.tag = indexPath.row
        
        if let playingCell = currentPlayingIndex, playingCell == indexPath.row {
            cell.firstBtnOutlet.setImage(UIImage(named: "pauseButtonPack.png"), for:
                                            .normal)
        } else {
            cell.firstBtnOutlet.setImage(UIImage(named: "playButtonPack.png"), for:
                                            .normal)
        }
        return cell
    }

每行播放歌曲的按钮：

extension BPLibraryViewController: BeatPackLibraryDelegate {
    
    func didTapFirstSong(cell: BeatPackLibraryCell) {
        let indexPath = self.tableView.indexPath(for: cell)
        if currentPlayingIndex == cell.tag {
            audioPlayer.pause()
            currentPlayingIndex = nil
        } else { //IF PAUSE BUTTON
            playLoop(songName: songs[cell.tag])
            currentPlayingIndex = cell.tag
        }
        tableView.reloadData()
        print("Done")
    }

那么如何从本地 JSON 文件加载歌曲并将其显示在每一行上。

Answer 1

首先，playLoop 方法无法工作，因为 withExtension 参数中的文件扩展名必须在不带点的情况下指定。

我的建议是在 Loop 结构中添加一个计算属性以获得应用程序包中的 URL 例如

struct Loop : Decodable {
    let name, producer, count, genre, imagename, songName : String
    private enum CodingKeys : String, CodingKey { case name, producer, count, genre, imagename, songName }
    
    var songURL : URL {
        let components = songName.components(separatedBy: ".")
        guard components.count == 2, 
             let url = Bundle.main.url(forResource: components[0], withExtension: components[1]) else { fatalError("Audio file is missing") }
        return url
    }
}

需要 CodingKeys 才能将 songURL 排除在解码之外。

如果所有音频文件都是 mp3 文件，您甚至可以省略 JSON 中的扩展名，并且计算出的属性会变得更短

struct Loop : Decodable {
    let name, producer, count, genre, imagename, songName : String
    private enum CodingKeys : String, CodingKey { case name, producer, count, genre, imagename, songName }
    
   var songURL : URL {
        guard let url = Bundle.main.url(forResource: songName, withExtension: "mp3") else { fatalError("Audio file is missing") }
        return url
   }
}

现在您可以将 playLoop 方法更改为

func playLoop(songURL: URL) {
    audioPlayer = try! AVAudioPlayer(contentsOf: songURL)
    audioPlayer.play()
    print(songURL.lastPathComponent)
}

并在点击方法中播放歌曲

else { //IF PAUSE BUTTON
     playLoop(songURL: loopsName[indexPath.row].songURL)
     currentPlayingIndex = cell.tag
}

不需要方法gettingSongName()。顺便说一下可以写成2行

func gettingSongName() {
    guard let mp3URLs = Bundle.main.urls(forResourcesWithExtension: "mo3", subdirectory: nil) else { return }
    songs = mp3URLs.map{[=14=].deletingPathExtension().lastPathComponent} 
}

备注：

切勿在文件系统 URL 上调用 absoluteString，您只需使用 path.
将您的数据源数组命名为 loops 并将 cellforRow 中的项目命名为 loop。你的命名很混乱。

使用 swift 从本地 JSON 文件点击 table 视图中的按钮播放歌曲

Play songs by tapping the button in table view from local JSON file using swift

parsing

json

uitableview

ios

swift