Automatically playing next audio file from collection view - swift

Question

I'm building audio book app.
I have play button inside my collection view cell where users see list of all mp3 files. When user presses this button (play button) - I'm sending data of track to my player class and music file starts to play. I'm using global variables to send track details to my player.
Here's my code:
extension ChapterDetailsViewController: AliaCellDelegate {
func playAlia(cell: AliaCell) {
NotificationCenter.default.post(name: NSNotification.Name(rawValue: "playAudio"), object: nil)
}
}
I need to implement such functionality: When track comes to an end - automatically play next file from same list. For this, I have this method inside my player class, that informs me, when it has finished playing:
func playerDidFinishPlaying(note: NSNotification) {
print("Finished playing")
}
But I don't know how to call func playAlia(cell: AliaCell) inside func playerDidFinishPlaying(note: NSNotification) in my player class and pass details of the next track from my collection view.
For now I have created only:
NotificationCenter.default.addObserver(self, selector: #selector(playNext), name: NSNotification.Name(rawValue: "playNext"), object: nil) but what should I do next?

Answer 1

A simple solution is to keep track of existing track within your source model. The example makes plenty of assumptions and is not it not complete.
struct Track {
let url: URL
let title: String
let artist: String
}
class AudioPlayer: UIViewController {
var currentTrackIndex: Int = 0
let tracks: [Track] = [Track(), Track(), Track()]
let player: AVPlayer()
// table view delegate for row selection
override func tableView(_ tableView: UITableView,
didSelectRowAt indexPath: IndexPath) {
// assuming single section
currentTrackIndex = indexPath.row
playTrack(at: currentTrackIndex)
}
func playTrack(at index: Int) {
let nextTrack = tracks[index]
let nextItem = AVPlayerItem(url: nextTrack.url)
player.replaceCurrentItem(with: nextItem)
}
func playerDidFinishPlaying(note: NSNotification) {
// add logic to handle out of bounds index for array
currentTrackIndex += 1
playTrack(at: currentTrackIndex)
}
}