Play IOS Music Library Content Using AVFoundation

I'm attempting to write an IOS app that will play my iPhone music library content, showing artwork, and "announcing" title, artist, etc.

I have it working nicely using Apple's Media Player framework. I can display Playlist names and queue the songs in a selected Playlist. I use the "MPMusicPlayerControllerNowPlayingItemDidChange" observer notification to pause playback, retrieve metadata, and do the announcements via AVSpeechSynthesizer. I was a happy camper until I ran into the dreaded "Media Player framwork doesn't respond to observer notifications in background" issue.

So, I started looking at the AVFoundation Framework. I found a sample that plays local song files via URLs in the background and. I'm failing miserably in attempting to retrieve Music Library content via the AVFoundation. I have also failed in supplying content retrieved via the Media Player framework to the AVFoundation player. (Note: The URLs retrieved from MPMediaItem are of a bogus "ipod-library://item/item.m4a?id=#########################" format. Creating AVPlayerItem with this "URL" doesn't work.)

Has anyone managed to accomplish this? I'm developing for my own usage. I have no intention of posting the app in Apple's App Store, so I'm willing to use hidden APIs or un-Apple approved methodology.

A Swift code example would be great. (Objective-C not so much)

Having fetched an MPMediaItem from the user's library, obtain its assetURL. Creating an AVPlayer from the resulting URL does work.

Actual code from one of my example apps:

func oneSong () -> (URL?, String?) {
    let query = MPMediaQuery.songs()
    // always need to filter out songs that aren't present
    let isPresent = MPMediaPropertyPredicate(value:false,
        forProperty:MPMediaItemPropertyIsCloudItem,
        comparisonType:.equalTo)
    query.addFilterPredicate(isPresent)
    let item = query.items?[0]
    return (item?.assetURL, item?.title)
}
@IBAction func doPlayOneSongAVPlayer (_ sender: Any) {
    let (url, title) = self.oneSong()
    if let url = url, let title = title {
        self.avplayer = AVPlayer(url:url)
        self.avplayer.play()
        MPNowPlayingInfoCenter.default().nowPlayingInfo = [
            MPMediaItemPropertyTitle : title
        ]
    }
}