使用 MPMusicPlayerApplicationController 时如何更新 MPNowPlayingInfoCenter

Question

我正在尝试使用我正在从 Apple Music 播放的曲目的歌曲信息来更新 MPNowPlayingInfoCenter。我做了以下事情：

将我的背景模式设置为："Audio, Airplay, and Picture in Picture"、

正确设置我的 AVAudioSession 类别：

let session = AVAudioSession.sharedInstance()

do {
    try session.setCategory(AVAudioSessionCategoryPlayback, with: [])
    try session.setActive(true)
} catch let error as NSError {
    print("Failed to set the audio session category and mode: \(error.localizedDescription)")
}

设置 MPRemoteCommandCenter 以响应远程命令：

let commandCenter = MPRemoteCommandCenter.shared();
commandCenter.playCommand.isEnabled = true
commandCenter.playCommand.addTarget {event in
    self.player.play()
    return .success
}
commandCenter.pauseCommand.isEnabled = true
commandCenter.pauseCommand.addTarget {event in
    self.player.pause()
    return .success
}
commandCenter.nextTrackCommand.isEnabled = true
commandCenter.nextTrackCommand.addTarget {event in
    self.goForward()
    return .success
}
commandCenter.previousTrackCommand.isEnabled = true
commandCenter.previousTrackCommand.addTarget {event in
    self.goBack()
    return .success
}

并在开始时和有播放事件时使用正确的信息更新 MPNowPlayingInfoCenter：

let info: [String:Any] = [
    MPMediaItemPropertyAlbumTitle : albumTitle,
    MPNowPlayingInfoCollectionIdentifier : albumId,
    MPMediaItemPropertyArtist : artistName,
    MPNowPlayingInfoPropertyMediaType : mediaType,
    MPMediaItemPropertyPersistentID : trackId,
    MPMediaItemPropertyTitle : trackTitle,
    MPMediaItemPropertyPlaybackDuration : trackDuration,
    MPNowPlayingInfoPropertyExternalContentIdentifier : trackId,
    MPNowPlayingInfoPropertyPlaybackRate : isPlaying ? 1.0 : 0.0,
    MPNowPlayingInfoPropertyPlaybackProgress : 0.5,
    MPMediaItemPropertyArtwork : MPMediaItemArtwork(boundsSize: CGSize(width: 100, height: 100), requestHandler: { (size: CGSize) -> UIImage in
        return UIImage(named: "play")! // dummy purposes
    })
]

let infoCenter = MPNowPlayingInfoCenter.default()
infoCenter.nowPlayingInfo = info
infoCenter.playbackState = isPlaying ? .playing : .paused

我还需要做什么才能让歌曲信息显示在控制中心和锁定屏幕上？

Answer 1

事实证明代码是 100% 正确的，但在 iOS 11（11.3 之前的版本）中是一个错误。随着本周 11.3 的正式发布，上面的代码现在可以按照 Apple 的预期运行 MPMusicPlayerApplicationController。

使用 MPMusicPlayerApplicationController 时如何更新 MPNowPlayingInfoCenter

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