我认为这很简单，只要在视图控制器类中保留一个BOOL属性，当单击播放/恢复按钮时将其设置为YES，当按下停止/暂停按钮时将其设置为NO。

它由以下this link组成：

if ((player.rate != 0) && (player.error == nil)) {
        // player is playing
    }else {
//notplaying
}

只需添加布尔变量，并根据您检查是否暂停音频.
例如：

var isAudioPaused = false//Add this on top

//Pause audio
func pauseAudio() {
    if isAudioPaused == false {
        if audioPlayer?.isPlaying == true {//Check is audio playing
            audioPlayer?.pause()//Pause audio
            isAudioPaused = true
            btnPauseAudio.setTitle("Play Audio", for: .normal)
        }
    } else {
        audioPlayer?.play()//Play audio
        isAudioPaused = false
        btnPauseAudio.setTitle("Pause Audio", for: .normal)
    }
}

您可以通过代码player.isPlaying && player.duration != 0检查播放器是否暂停

func buttonOneClicked(button: UIButton)  {
    if player.isPlaying && player.duration != 0 {
       button.setImage(UIImage(systemName: "stop"), for: .normal)
       player.pause()
    }
    else{
       button.setImage(UIImage(systemName: "play"), for: .normal)
       player.play()
    }
}