快速的AVPlayer状态监听器

Question

I want to know how to get the state of my player (AVPlayer) (buffering, playing, stopped, error) and update the ui according to those states (including the player on the lock screen). How exactly should I do it?

I have a label that may contain: "Buffering...", "Playing", "Stopped" or "Error".

Basically, I have the following:

MediaPlayer :

import Foundation
import AVFoundation

class MediaPlayer {

    static let sharedInstance = MediaPlayer()
    fileprivate var player = AVPlayer(url: URL(string: "my_hls_stream_url_here")!)
    fileprivate var isPlaying = false

    func play() {
        player.play()
        isPlaying = true
    }

    func pause() {
        player.pause()
        isPlaying = false
    }

    func toggle() {
        if isPlaying == true {
            pause()
        } else {
            play()
        }
    }

    func currentlyPlaying() -> Bool {
        return isPlaying
    }

}

PlayerViewController :

class PlayerViewController: UIViewController {

    @IBOutlet weak var label: UILabel!
    @IBAction func playStopButtonAction(_ sender: UIButton) {
        MediaPlayer.sharedInstance.toggle()
    }

    override func viewDidLoad() {
        super.viewDidLoad()

        label.text = "Disconnected"

        do {
            try AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback)
            try AVAudioSession.sharedInstance().setActive(true)

            print("Audio session ok\n")
        } catch {
            print("Error: Audio session.\n")
        }

        // Show only play/pause button on the lock screen
        if #available(iOS 9.1, *) {

            let center = MPRemoteCommandCenter.shared()

            [center.previousTrackCommand, center.nextTrackCommand, center.seekForwardCommand, center.seekBackwardCommand, center.skipForwardCommand, center.skipBackwardCommand, center.ratingCommand, center.changePlaybackRateCommand, center.likeCommand, center.dislikeCommand, center.bookmarkCommand, center.changePlaybackPositionCommand].forEach {
                $0.isEnabled = false
            }

            center.togglePlayPauseCommand.addTarget { (commandEvent) -> MPRemoteCommandHandlerStatus in
                MediaPlayer.sharedInstance.toggle()
                return MPRemoteCommandHandlerStatus.success
            }

            center.playCommand.addTarget { (commandEvent) -> MPRemoteCommandHandlerStatus in
                MediaPlayer.sharedInstance.play()
                return MPRemoteCommandHandlerStatus.success
            }

            center.pauseCommand.addTarget { (commandEvent) -> MPRemoteCommandHandlerStatus in
                MediaPlayer.sharedInstance.pause()
                return MPRemoteCommandHandlerStatus.success
            }

        } else {
            // Fallback on earlier versions
            print("Error (MPRemoteCommandCenter)")
        }


    }


    override func remoteControlReceived(with event: UIEvent?) {
        guard let event = event else {
            print("No event\n")
            return
        }
        guard event.type == UIEventType.remoteControl else {
            print("Another event received\n")
            return
        }
        switch event.subtype {
        case UIEventSubtype.remoteControlPlay:
            print("'Play' event received\n")
        case UIEventSubtype.remoteControlPause:
            print("'Pause' event received\n")
        case UIEventSubtype.remoteControlTogglePlayPause:
            print("'Toggle' event received\n")
        default:
            print("\(event.subtype)\n")
        }
    }

}

Answer 1

I think you could use the timeControlStatus property of AVPlayer . According to the doc it can be paused , waitingToPlayAtSpecifiedRate which is basically what you call buffering or playing .

If you really need the error state, you could observe the error property or whether the status property is set to failed .

A simple KVO observer on these properties would do the trick.

Answer 2

A place to start could be through using the AVPlayer's "status" property. It is an enumeration that contains the following values (this is taken directly from the documentation):

1. 'unknown' : Indicates that the status of the player is not yet known because it has not tried to load new media resources for playback.

2. 'readyToPlay' : Indicates that the player is ready to play AVPlayerItem instances.

3. 'failed' : Indicates that the player can no longer play AVPlayerItem instances because of an error.

As to how you could tell if the content is actually playing, you could just use boolean checks as it seems you have partially implemented. For pausing and stopping, you could just keep the file loaded for pause, and delete the file for stop that way you could differentiate the two.

For buffering, if the enum is not unknown or readyToPlay then that theoretically should mean that there is a file being attached but is not quite ready to play (ie buffering).