Swift Music Player

private func playPauseActionHandler(completion: ((Bool)->Void)? = nil) {

        if radio.player == nil {
            configureAudioSession() // call just before playing first audio
        }

        if let url = URL(string: radio.streamURL) {

            radio.playerItem = AVPlayerItem(url: url)
            radio.player = AVPlayer(playerItem: radio.playerItem)

            session.activate(options: []) { (success, error) in

                guard error == nil else {
                    print("*** An error occurred: \(error!.localizedDescription) ***")
                    completion?(false)
                    return
                }

                if playing == false {
                    radio.player?.play()
                    playing = true
                } else {
                    radio.player?.pause()
                    playing = false
                }


                completion?(success)
            }
        }
    }

    private var audioStreamIsPlaying: Bool {

        if let audioPlayer = radio.player {
            return audioPlayer.rate > 0 // audio is playing
        }

        return false
    }

    private func configureAudioSession() {

        do {
            try session.setCategory(AVAudioSession.Category.playback,
                                    mode: .default,
                                    policy: .longFormAudio,
                                    options: [])
        } catch let error {
            fatalError("*** Unable to set up the audio session: \(error.localizedDescription) ***")
        }
    }