ios - 一旦录音机使用 AudioKit 在 Swift 中完成录音，如何实现监听器或 while(true) 以停止滚动波形图

Question

我有一个系统，它使用 AudioKit 中的各种类来记录麦克风输入并将其保存到文件中，最长持续时间为 30 秒，同时在记录期间使用 EZAudioPlot 将输出波形绘制到波形图上。

我的问题是我使用的是 Snapchat 风格的录制按钮，该按钮开始录制/绘制触摸事件并停止录制/绘制触摸(内部和外部)事件 - 这意味着当用户持续按住录音按钮超过最大持续时间(有时会这样做)，尽管录音机已完成，但麦克风输出的波形仍在绘制。我在问 Swift/AudioKit 中是否有一种方法可以不断地“监听”录音机停止录音，类似于类似的东西

while true
{
    if recorder.isRecording() == false
    {
        plot.pause()
    }
}  

在按下按钮之后但在释放按钮之前？如果有某种方法可以无限期地收听录音机是否在按下按钮和释放按钮之间 完成录音，这将很容易解决我的问题。这种功能是否以某种形式存在于 Swift 或 AudioKit 中？

我的代码如下(无关代码省略):

import UIKit
import AudioKit
import AudioKitUI

// Define maximum recording time in seconds

let maxRecordingTime = 30.0

class ViewController: UIViewController
{
    var microphone : AKMicrophone!
    var mixer : AKMixer!
    var waveformBooster: AKBooster!
    var outputBooster : AKBooster!
    var exportTape : AKAudioFile!
    var recorder : AKNodeRecorder!
    var player : AKClipPlayer!
    var circleView : CircleView!
    var plot : AKNodeOutputPlot!

    @IBOutlet var startRecordingButton: CircularButton!
    @IBOutlet var playRecordingButton: UIButton!
    @IBOutlet var waveformPlot: EZAudioPlot!

    override func viewDidLoad()
    {
        super.viewDidLoad()

        microphone = AKMicrophone()
        mixer = AKMixer(microphone)

        // Initialise booster to set monitoring level to zero - this ensures that
        // microphone output is recorded but not sent to main audio output

        outputBooster = AKBooster(mixer)
        outputBooster.gain = 0

        // Initialise booster to set waveform display gain so that waveform can be set to display
        // only when the app is recording

        waveformBooster = AKBooster(microphone)
        waveformBooster.gain = 0

        AudioKit.output = outputBooster
        try!AudioKit.start()

        // Initialise file to store recorder output and set recorder to route mixer
        // output to file

        exportTape = try! AKAudioFile(name: "ExportTape")
        recorder = try! AKNodeRecorder(node: mixer, file: exportTape)

        recorder.durationToRecord = maxRecordingTime

        plot = AKNodeOutputPlot(waveformBooster, frame: waveformPlot.bounds)
        setupWaveformPlot()
    }

    @IBAction func startRecording(_ sender: UIButton)
    {
        // Delete contents of output file so it can be rewritten

        try! recorder.reset()

        // Perform various tasks related to getting the plot ready
        // to be rewritten to in the event of several recordings being made

        updateWaveformPlot()

        // Start the microphone and

        microphone.start()
        waveformBooster.gain = 1

        animateRecordingButton()

        do
        {
            try recorder?.record()
        } catch
        {
            AKLog("Couldn't record")
        }
    }

    @IBAction func stopRecording(_ sender: UIButton)
    {
        microphone.stop()
        waveformBooster.gain = 0
        recorder.stop()

        plot.pause()
    }

    @IBAction func playRecording(_ sender: UIButton)
    {
        let player = try! AKAudioPlayer(file: exportTape)

        if player.isStarted == false
        {
            AudioKit.output = player
            player.play()
        }
    }

    func setupWaveformPlot()
    {
        plot.plotType = .rolling
        plot.clipsToBounds = true
        plot.shouldFill = true
        plot.shouldMirror = true
        plot.color = UIColor.white
        plot.backgroundColor = UIColor.black

        // Set the gain of the plot to control range of values displayed on the waveform plot

        plot.gain = 25
        waveformPlot.addSubview(plot)
    }

    func updateWaveformPlot()
    {
        plot.clear()
        plot.resume()

        // Set rolling history length to correct value for 30s
        // such that waveform fills whole plot with no scrolling

        plot.setRollingHistoryLength(Int32(Float(1284)))
    }
}

Answer 1

我最终用定时器实现了我想要的行为，比如:

var recordingTimer = Timer!
let maxRecordingTime = 30.0    

if recordingTimer == nil
                {
                    recordingTimer = Timer.scheduledTimer(withTimeInterval: maxRecordingTime, repeats: false)
                    {
                        timer in
                        self.plot.pause()
                    }