Question

我有一个声音文件，它听起来是哔哔声，我必须根据某些条件改变它的音高重复播放这个声音。我正在使用AVAudioEngine，AVAudioPlayerNode和AVAudioUnitTimePitch来实现这一目标。我的视图中有两个按钮，即播放和停止。当我第一次按下“播放”按钮时，声音重复播放，但是在单击“停止”按钮一次然后再次单击“播放”按钮后，声音不会播放并且也没有出现错误。我一直在研究这个问题但是无法得到解决方案而且我来到了这里。你能帮我解决这个问题吗？或者我的问题有其他替代解决方案吗？我的代码如下：

import UIKit
import AVFoundation

class ViewController: UIViewController {

    let engine = AVAudioEngine()
    let audioPlayer = AVAudioPlayerNode()
    let pitchUnit = AVAudioUnitTimePitch()

    var avAudioFile: AVAudioFile!

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.

        let path = Bundle.main.path(forResource: "Beep", ofType: "wav")!
        let url = NSURL.init(fileURLWithPath: path)
        avAudioFile = try? AVAudioFile(forReading: url as URL)

        setup()
    }

    func setup() {
        engine.attach(audioPlayer)
        engine.attach(pitchUnit)
        engine.connect(audioPlayer, to: pitchUnit, format: nil)
        engine.connect(pitchUnit, to:engine.mainMixerNode, format: nil)

        try? engine.start()

        audioPlayer.volume = 1.0
        audioPlayer.play()

    }
    @IBAction func playSound(_ sender: UIButton) {

        pitchUnit.pitch = 1

        // interrupt playing sound if you have to
        if audioPlayer.isPlaying {
            audioPlayer.stop()
            audioPlayer.play()
        }
        let buffer = AVAudioPCMBuffer(pcmFormat: avAudioFile.processingFormat, frameCapacity: AVAudioFrameCount(avAudioFile.length))
        try? avAudioFile.read(into: buffer!)
        audioPlayer.scheduleBuffer(buffer!, at: nil, options: AVAudioPlayerNodeBufferOptions.loops, completionHandler: nil)
    }

    @IBAction func stopSound(_ sender: UIButton) {
        audioPlayer.stop()
    }
}

Answer 1

问题在于你的playSound功能。

#text

只有在播放器播放时才试播。所以没有任何意义。你可以删除这些行，只需使用它。

// interrupt playing sound if you have to
if audioPlayer.isPlaying {
    audioPlayer.stop()
    audioPlayer.play()
}

声音仅在iOS中使用AVAudioEngine首次播放

1 个答案: