AVAudioPlayer on Lock Screen

问题

I've implemented an audio player using AVAudioPlayer (not AVPlayer). I'm able to handle the remote control events with the following method. It works quite alright so far, however I see two more subtypes for these events: UIEventSubtypeRemoteControlEndSeekingForward and UIEventSubtypeRemoteControlEndSeekingBackward.

- (void)remoteControlReceivedWithEvent:(UIEvent *)event {
    //if it is a remote control event handle it correctly
    if (event.type == UIEventTypeRemoteControl)
    {
        if (event.subtype == UIEventSubtypeRemoteControlPlay)
        {
            [self playAudio];
        }
        else if (event.subtype == UIEventSubtypeRemoteControlPause)
        {
            [self pauseAudio];
        }
        else if (event.subtype == UIEventSubtypeRemoteControlTogglePlayPause)
        {
            [self togglePlayPause];
        }
        else if (event.subtype == UIEventSubtypeRemoteControlBeginSeekingBackward)
        {
            [self rewindTheAudio]; //this method rewinds the audio by 15 seconds.
        }
        else if (event.subtype == UIEventSubtypeRemoteControlBeginSeekingForward)
        {
            [self fastForwardTheAudio]; //this method fast-forwards the audio by 15 seconds.
        }

}

So the questions:

1. In order to have things work right, am I supposed to implement those two subtypes, too?

2. This method only enables the rewind, play/pause, and fast forward buttons on lock screen, but it doesn't display the file title, artwork, and duration. How can I display that info using AVAudioPlayer or AVAudioSession (I don't really want one more library/API to implement this)?

   2-a. I discovered MPNowPlayingInfoCenter while searching and I don't know much about it. Do I have to use it to implement those stuff above? :-[

回答1:

You are correct, MPNowPlayingInfoCenter is the only way to do this. So go ahead and link with MediaPlayer.framework. In the class that handles playing tracks, import <MediaPlayer/MediaPlayer.h>. Whenever your track changes, do this:

NSDictionary *info = @{ MPMediaItemPropertyArtist: artistName,
                            MPMediaItemPropertyAlbumTitle: albumName,
                            MPMediaItemPropertyTitle: songName };

    [MPNowPlayingInfoCenter defaultCenter].nowPlayingInfo = info;

来源：https://stackoverflow.com/questions/20363058/avaudioplayer-on-lock-screen