如何在单击下一首按钮时播放下一首歌曲

Question

我正在使用 AVAudioPlayer() 创建音乐播放器所以我有多个 JSON 格式的音频文件 url 所以我在 tableview 中显示所有内容然后在 didSelect 我正在播放选定的歌曲但我想在按钮上播放下一首歌曲点击这里是我在 didSelect

上播放歌曲的代码

did选择代码

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
        let urlstring = songs[indexPath.row]
        let strnew = urlstring.replacingOccurrences(of: "\"", with: "")
        downloadFileFromURL(url: strnew)
}

这是我从 URL

下载音频的功能

func downloadFileFromURL(url: String)  {

    if let audioUrl = URL(string: url) {

        let documentsDirectoryURL =  FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!

        let destinationUrl = documentsDirectoryURL.appendingPathComponent(audioUrl.lastPathComponent)
        print(destinationUrl)

        if FileManager.default.fileExists(atPath: destinationUrl.path) {
            print("The file already exists at path")
            self.play(url: destinationUrl)
        } else {
            URLSession.shared.downloadTask(with: audioUrl, completionHandler: { (location, response, error) -> Void in
                guard let location = location, error == nil else { return }
                do {
                    try FileManager.default.moveItem(at: location, to: destinationUrl)

                    self.play(url: destinationUrl)
                    print("File moved to documents folder")
                } catch let error as NSError {
                    print(error.localizedDescription)
                }
            }).resume()
        }
    }
}

使用下面的代码我正在播放音频

func play(url: URL) {

    print("playing \(url)")

    do {

        audioPlayer = try AVAudioPlayer(contentsOf: url)
        audioPlayer.prepareToPlay()
        audioPlayer.volume = 1.0
        audioPlayer.play()

    } catch let error as NSError {

        print("playing error: \(error.localizedDescription)")

    } catch {

        print("AVAudioPlayer init failed")
    }
}

但我无法理解如何在单击下一首按钮时播放下一首歌曲我在下面分享我的 User Interface 的屏幕截图

在 didSelect 我可以播放选定的歌曲但是如何管理下一首上一首我不确定请帮助我。

Answer 1

在ViewController中只维护一个索引值。

喜欢：

var currentIndex = 0

在 didSelect 方法中用 indexPath 行值更新当前索引值

func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
   currentIndex = indexPath.row
   loadUrl()
}

使用另一种方法获取 URL 并播放歌曲。将

func loadUrl(){
    let urlstring = songs[currentIndex]
    let strnew = urlstring.replacingOccurrences(of: "\"", with: "")
    downloadFileFromURL(url: strnew)
}

对于 previous/next 按钮操作将是

@IBAction func nextBtnAction(_ sender: UIButton){
    if currentIndex + 1 < songs.count {
          currentIndex = currentIndex + 1
          loadUrl()
     }
}

@IBAction func previousBtnAction(_ sender: UIButton){
    if currentIndex != 0 {
          currentIndex = currentIndex - 1
          loadUrl()
     }
}

希望你明白。

Answer 2

加入你的ViewController

var currentPlayingIndex: Int?

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

    self.currentPlayingIndex = indexPath.row
    self.loadSongFromURL()
}
.....

//Button Action..
@IBAction func nextButtonAction(_ sender: Any){

    self.playSong(isForward: true)
}

@IBAction func previousButtonAction(_ sender: Any) {

    self.playSong(isForward: false)
}

private func playSong(isForward: Bool) {

    if currentPalyingIndex == nil { //Means not any song is playing
        currentPalyingIndex = 0
        self.loadSongFromURL()
    }
    else{

        if isForward {

            if self.currentPalyingIndex! < self.items.count-1 {
                self.currentPalyingIndex = self.currentPalyingIndex! + 1
                self.loadSongFromURL()
            }
            else {
                // handle situation while reach at last
            }
        }
        else {
            if self.currentPalyingIndex! > 0 {
                self.currentPalyingIndex = self.currentPalyingIndex! - 1
                self.loadSongFromURL()
            }
            else {
                // handle situation while reach at 0
            }
        }
    }
}

// Load Song
func loadSongFromURL(){

   let urlstring = songs[self.currentPalyingIndex]
   let strnew = urlstring.replacingOccurrences(of: "\"", with: "")
   downloadFileFromURL(url: strnew)
}

如何在单击下一首按钮时播放下一首歌曲

how to play next song on next button click

ios

swift

avaudioplayer

avaudiosession