在两个方法中调用时，Swift在Control Center中更新媒体元数据不起作用

Question

我有两种方法可以在CC/Lock screen中显示媒体信息

func updateGeneralMetadata() {
        guard player.url != nil, let _ = player.url else {
            nowPlayingInfoCenter.nowPlayingInfo = nil
            return
        }
        let item = currentItem
        var rating = ""
        for _ in 0 ..< item!.rating{
            rating.append("*")
        }
        if item?.assetURL != nil{
            MPNowPlayingInfoCenter.default().nowPlayingInfo = [
                MPMediaItemPropertyTitle: item?.value(forProperty: MPMediaItemPropertyTitle)!,
                MPMediaItemPropertyArtist: item?.value(forProperty: MPMediaItemPropertyArtist)!,
                MPMediaItemPropertyAlbumTitle: rating,
                MPMediaItemPropertyArtwork: item?.artwork ?? UIImage()
            ]
        }
    }

func updatePlaybackRateData(){
        guard currentItem?.assetURL != nil else {
            duration = 0
            nowPlayingInfoCenter.nowPlayingInfo = nil
            return
        }
        duration = Float(player.duration)
        let item = currentItem
        MPNowPlayingInfoCenter.default().nowPlayingInfo = [
                    MPNowPlayingInfoPropertyElapsedPlaybackTime: player.currentTime,
                    MPNowPlayingInfoPropertyPlaybackRate: player.rate,
                    MPMediaItemPropertyPlaybackDuration: item?.playbackDuration
                ]
}

和播放媒体的功能

func play(){
player.play()
timer = Timer.scheduledTimer(timeInterval: 1.0, target: self, selector: #selector(Plum.updatePlaybackRateData), userInfo: nil, repeats: true)
        timer.fire()
        NotificationCenter.default.post(name: Plum.playBackStateChanged, object: nil, userInfo: ["Artist": "Title"])
        updateGeneralMetadata()
}

如你所见，我希望每秒更新一次播放速率，并且仅在媒体文件发生更改时更新一般元数据。当我有像那样的两个函数时，似乎只有updateGeneralData()有效，因为当我把所有的信息，如标题，艺术家，albumTitle，艺术作品，currentTime，速率和持续时间都显示在updatePlaybackRateData()中时，LS/CC上没有回放时间条，但我想在两个方法之间拆分这种功能性，以便只有必要的信息每秒更新一次。

Answer 1

显然，下面的解决方案解决了这个问题。我创建了一个新的常量

let infoCC = MPNowPlayingInfoCenter.default()

并将方法更改为：

func updateGeneralMetadata() {
        guard player.url != nil, let _ = player.url else {
            infoCC.nowPlayingInfo = nil
            return
        }
        let item = currentItem
        var nowPlayingInfo = infoCC.nowPlayingInfo ?? [String: Any]()
        nowPlayingInfo[MPMediaItemPropertyTitle] = item?.title
        nowPlayingInfo[MPMediaItemPropertyArtist] = item?.albumArtist
        nowPlayingInfo[MPMediaItemPropertyAlbumTitle] = item?.albumTitle
        nowPlayingInfo[MPMediaItemPropertyArtwork] = item?.artwork
        infoCC.nowPlayingInfo = nowPlayingInfo
    }

    func updatePlaybackRateData(){
        guard currentItem?.assetURL != nil else {
            duration = 0
            infoCC.nowPlayingInfo = nil
            return
        }
        var nowPlayingInfo = infoCC.nowPlayingInfo ?? [String: Any]()
        duration = Float(player.duration)
        let item = currentItem
        nowPlayingInfo[MPNowPlayingInfoPropertyElapsedPlaybackTime] = player.currentTime
        nowPlayingInfo[MPNowPlayingInfoPropertyPlaybackRate] = player.rate
        nowPlayingInfo[MPMediaItemPropertyPlaybackDuration] = player.duration
        infoCC.nowPlayingInfo = nowPlayingInfo
}

希望它能在未来帮助某些人