如何在来电结束后让应用恢复播放音频？

Question

应用正在播放音频（处于活动或背景模式）。来电时，系统停止播放音频。通话结束后如何重新通过应用程序继续播放音频？

这是苹果公司的指南：

https://developer.apple.com/documentation/avfoundation/avaudiosession#//apple_ref/doc/uid/TP40008240-CH1-DontLinkElementID_3

https://developer.apple.com/documentation/avfoundation/avaudiosession/responding_to_audio_session_interruptions

遵循指南，我得到了以下代码：

private func setupAudioSession() {
    do {

        try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback, with: .mixWithOthers)
        try AVAudioSession.sharedInstance().setActive(true)

        setupAudioNotifications()

    } catch {
        print(error)
    }
}

private func setupAudioNotifications() {
    NotificationCenter.default.addObserver(self, selector: #selector(handleInterruption), name: .AVAudioSessionInterruption, object: nil)
}

@objc func handleInterruption(notification: Notification) {

    guard let userInfo = notification.userInfo,
        let typeValue = userInfo[AVAudioSessionInterruptionTypeKey] as? UInt,
        let type = AVAudioSessionInterruptionType(rawValue: typeValue) else {
            return
    }

    if type == .began { // NOTE: it works
        // Interruption began, take appropriate actions
        Player.shared.stop()

    } else if type == .ended { // NOTE: it doesn't work
        if let optionsValue = userInfo[AVAudioSessionInterruptionOptionKey] as? UInt {
            let options = AVAudioSessionInterruptionOptions(rawValue: optionsValue)
            if options.contains(.shouldResume) {
                // Interruption Ended - playback should resume
                Player.shared.start()
            } else {
                // Interruption Ended - playback should NOT resume
            }
        }
    }
}

.began总是会触发并且播放器停止，但是由于某种原因，.end不会触发，并且继续播放音频的命令也不会发出。

测试方式：我从另一台设备打入电话（并且.began事件触发），在发出哔声之后，我结束了从另一台设备的呼叫（在这种情况下没有handleInterruption（）调用）