ios - 使用 AVAudioEngine 循环音频

Question

我一直在 obj-c 中工作，但我想快速恢复头脑。我的代码即将完成，但我只是不知道如何循环我的 wav。播放一次后就停止了。我找到了一些说明，但还没有找到适合我的代码的解决方案。我希望有人知道答案并可以帮助我。所以问题是:当按下 @IBAction func playButtonTapped 时，我必须做什么才能使我的 wav 循环？为了确定起见，我将提供所有代码。预先感谢:-)

class ViewController: UIViewController {

    @IBOutlet var startAllButton: UIButton!
    var audioEngine = AVAudioEngine()
    var playerNode = AVAudioPlayerNode()



    let timeShift = AVAudioUnitTimePitch()
    let pedoMeter = CMPedometer()
    let bpm: Float = 110


    var avgStarted: Bool = false

    var steps: Int = 0
    var timer = Timer()
    var adjustedBpm: Float = 110

    var timerCount = 10 {
        didSet {
            if timerCount == 0 {
                stopCountingSteps()


            }
        }
    }

    var lastTap: Date? = nil

    @IBOutlet weak var tempoTap: UIButton!
    @IBOutlet weak var slider: UISlider!
    @IBOutlet weak var label: UILabel!
    @IBOutlet weak var playButton: UIButton!
    @IBOutlet weak var timerLabel: UILabel!
    @IBOutlet weak var stepCountLabel: UILabel!
    @IBOutlet weak var avgLabel: UIButton!

    override func viewDidLoad() {
        super.viewDidLoad()
        setup()
    }

    func setup() {
        label.text = "110"
        audioEngine.attach(playerNode)
        audioEngine.attach(timeShift)
        audioEngine.connect(playerNode, to: timeShift, format: nil)
        audioEngine.connect(timeShift, to: audioEngine.mainMixerNode, format: nil)
        audioEngine.prepare()
        timerLabel.text = ""
        stepCountLabel.text = ""
        do {
            try audioEngine.start()
        } catch {
            print("Could not start audio engine")
        }
    }


    @IBAction func sliderValueChanged(_ sender: UISlider) {
        label.text = String(sender.value)



        self.label.text = String(format:"%.f", sender.value)

        adjustedBpm = sender.value
        timeShift.rate = adjustedBpm/bpm

    }

    @IBAction func playButtonTapped(_ sender: Any) {


        let url = Bundle.main.url(forResource: "25loop110", withExtension: ".wav")
              if let url = url {
                  do {
                      let audioFile = try AVAudioFile(forReading: url)


                    timeShift.rate = adjustedBpm/bpm
                      playerNode.scheduleFile(audioFile, at: nil, completionHandler: nil)

                  } catch {
                      print("could not load audio file")
                  }
              } else {
                  print("could not load audio file")
              }
              playerNode.play()

    }

Answer 1

问题是这些行:

let audioFile = try AVAudioFile(forReading: url)
playerNode.scheduleFile(audioFile, at: nil, completionHandler: nil)

循环在哪里？无处。该代码播放该文件一次。

您无法在 AVAudioEngine 中循环播放文件。您使用缓冲区进行循环。您将文件读入缓冲区并调用 scheduleBuffer(buffer, at: nil, options: .loops)。