Swift：使用 AVPlayer 播放音频 - 音频未播放，无法听到音频

Question

我使用 AVPlayer 仅播放 mp3 音频文件。我正在使用我测试过的网址并且工作正常。我需要使用 AVPlayer，因为我需要以编程方式设置 UISlider，而且 AVPlayer 很方便。UISlider 在音频播放时工作和更新。音频可能正在播放，但我听不到声音。我这样说是因为 UISlider 正在工作。

更新：在模拟器上构建应用程序时，您可以听到音频。在设备上构建时出现问题 - 我的是 XS MAX。

屏幕录制链接 -> 访问：https ://streamable.com/nkbn8

我试过在 AVAudioPlayer 和音频播放中使用相同的 URL，你可以听到它。

private func setupAudioContent() {

    let urlString = "https://s3.amazonaws.com/kargopolov/kukushka.mp3"
    if let url = NSURL(string: urlString) {
        audioPlayer = AVPlayer(url: url as URL)

        let playerLayer = AVPlayerLayer(player: audioPlayer)
        self.layer.addSublayer(playerLayer)
        playerLayer.frame = self.frame

        audioPlayer?.play()
        audioPlayer?.volume = 1.0
        audioPlayer?.addObserver(self, forKeyPath: "currentItem.loadedTimeRanges", options: .new, context: nil)

        let interval = CMTime(value: 1, timescale: 2)
        audioPlayer?.addPeriodicTimeObserver(forInterval: interval, queue: DispatchQueue.main, using: { (progressTime) in

            let currentTime = CMTimeGetSeconds(progressTime)
            let currentTimeSecondsString = String(format: "%02d", Int(currentTime.truncatingRemainder(dividingBy: 60)))
            let currentTimeMinutesString = String(format: "%02d", Int(currentTime / 60))
            self.currentTimeLabel.text = "\(currentTimeMinutesString):\(currentTimeSecondsString)"

            if let duration = self.audioPlayer?.currentItem?.duration {
                let durationsSeconds = CMTimeGetSeconds(duration)

                self.audioSlider.value = Float(currentTime / durationsSeconds)
            }
        })
    }
}


override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
    if keyPath == "currentItem.loadedTimeRanges" {
        isAudioPlaying = true

        if let duration = audioPlayer?.currentItem?.duration {
            let seconds = CMTimeGetSeconds(duration)
            let secondsText = Int(seconds) % 60
            let minutesText = String(format: "%02d", Int(seconds) / 60)
            audioLengthLabel.text = "\(minutesText):\(secondsText)"
        }
    }
}


@objc func handleSliderChange() {
    if let duration = audioPlayer?.currentItem?.duration {
        let totalSeconds = CMTimeGetSeconds(duration)
        let value = Float64(audioSlider.value) * totalSeconds
        let seekTime = CMTime(value: Int64(value), timescale: 1)
        audioPlayer?.seek(to: seekTime, completionHandler: { (completedSeek) in
        })
    }
}

预期结果：听到音频播放

实际结果：听不到音频播放。似乎音频播放只是没有声音。

Answer 1

使用 AVPlayer 时，您应该确保您的设备未处于静音模式，因为即使您的音量达到最大，这也会导致不输出音频。

如果您想让您的设备保持静音模式并仍然播放音频，您可以在 .play() 之前使用以下代码：

do {
            try? AVAudioSession.sharedInstance().setCategory(.playback, mode: .default, options: [])
        }
        catch {
            // report for an error
            print(error)
        }