ios - 如何从同一个 AVAudioEngine 播放多个不同的音频文件？ (错误: !nodeimpl->HasEngineImpl())

Question

在我的应用程序中，我想每次按下 TableView 中的不同单元格时播放不同的音频文件。以下是我的实现，但我不断收到错误:

Terminating app due to uncaught exception 'com.apple.coreaudio.avfaudio', reason: 'required condition is false: !nodeimpl->HasEngineImpl()'

我认为这个错误意味着它正在崩溃，因为音频引擎已经包含该节点。但我不确定如何解决我的情况。

var audioPlayerFile : AVAudioFile!
var audioEngine = AVAudioEngine()
var pitchPlayer = AVAudioPlayerNode()
var timePitch = AVAudioUnitTimePitch()
var delay = AVAudioUnitDelay()

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

        pitchPlayer.stop()
        audioEngine.stop()
        audioEngine.reset()

    let filePathResource = myConversation.conversation[indexPath.row].fileName

    print("file:", filePathResource)
    if (filePathResource != nil) {
        setUpAudioFilePath(filePathRes: filePathResource!)
    }

    timePitch.pitch = 0
    delay.delayTime = 0

    //append more effect:
    audioEngine.connect(pitchPlayer, to: timePitch, format: audioPlayerFile.processingFormat)
    audioEngine.connect(timePitch, to: delay, format: audioPlayerFile.processingFormat)
    audioEngine.connect(delay, to: audioEngine.outputNode, format: audioPlayerFile.processingFormat)

    pitchPlayer.scheduleFile(audioPlayerFile, at: nil, completionHandler: nil)
    do { try audioEngine.start()}
    catch {
        print("Error: Starting Audio Engine")
    }

    pitchPlayer.play()

}

func setUpAudioFilePath (filePathRes: String) {

    if let filePath = Bundle.main.path(forResource: filePathRes, ofType: "m4a") {

        let filePathUrl = NSURL.fileURL(withPath: filePath)
        do { audioPlayerFile = try AVAudioFile(forReading: filePathUrl) }
        catch {
            print("Error: Reading Audio Player File")
        }
        audioEngine.attach(pitchPlayer)
        audioEngine.attach(timePitch)
        audioEngine.attach(delay)

    } else {
        print("Error: filePath is empty")
    }
}

Answer 1

我认为你需要混音器来播放多个音频。AVAudioEngine已经有与outputNode连接的混音器。试试这个

audioEngine.connect(pitchPlayer, to: timePitch, format: audioPlayerFile.processingFormat)
audioEngine.connect(timePitch, to: delay, format: audioPlayerFile.processingFormat)
audioEngine.connect(delay, to: audioEngine.mainMixerNode, format: audioPlayerFile.processingFormat)