How to Build an Audiobook Player App in SwiftUI

import SwiftData
import Foundation

@Model final class Book {
    var id: UUID = UUID()
    var title: String
    var author: String
    var fileURL: URL?
    var coverData: Data?
    var currentPosition: Double = 0   // seconds
    var duration: Double = 0
    var lastPlayedAt: Date?
    var isFinished: Bool = false

    @Relationship(deleteRule: .cascade)
    var bookmarks: [Bookmark] = []

    init(title: String, author: String) {
        self.title = title
        self.author = author
    }
}

@Model final class Bookmark {
    var id: UUID = UUID()
    var position: Double
    var note: String
    var createdAt: Date = Date.now

    init(position: Double, note: String = "") {
        self.position = position
        self.note = note
    }
}

struct PlayerView: View {
    @Bindable var book: Book
    @Environment(AudioPlayerService.self) var player

    var body: some View {
        VStack(spacing: 24) {
            if let data = book.coverData, let img = UIImage(data: data) {
                Image(uiImage: img)
                    .resizable().aspectRatio(1, contentMode: .fit)
                    .frame(maxWidth: 260).clipShape(RoundedRectangle(cornerRadius: 16))
            }
            VStack(spacing: 4) {
                Text(book.title).font(.headline)
                Text(book.author).font(.subheadline).foregroundStyle(.secondary)
            }
            Slider(value: $book.currentPosition, in: 0...max(book.duration, 1)) { editing in
                if !editing { player.seek(to: book.currentPosition) }
            }
            HStack {
                Text(Duration.seconds(book.currentPosition),
                     format: .units(width: .condensedAbbreviated))
                Spacer()
                Text(Duration.seconds(book.duration),
                     format: .units(width: .condensedAbbreviated))
            }.font(.caption.monospacedDigit()).foregroundStyle(.secondary)
            HStack(spacing: 40) {
                Button { player.skip(-15) } label: { Image(systemName: "gobackward.15").font(.title) }
                Button { player.isPlaying ? player.pause() : player.play(book) } label: {
                    Image(systemName: player.isPlaying ? "pause.fill" : "play.fill").font(.largeTitle)
                }
                Button { player.skip(30) } label: { Image(systemName: "goforward.30").font(.title) }
            }
            Button("Add Bookmark") { player.addBookmark() }.buttonStyle(.borderedProminent)
        }.padding()
    }
}

import AVFoundation, MediaPlayer, Observation

@Observable final class AudioPlayerService {
    private(set) var isPlaying = false
    private(set) var currentBook: Book?
    private var player: AVPlayer?
    private var timeObserver: Any?

    func play(_ book: Book) {
        guard let url = book.fileURL else { return }
        try? AVAudioSession.sharedInstance().setCategory(.playback, mode: .spokenAudio)
        try? AVAudioSession.sharedInstance().setActive(true)
        if currentBook?.id != book.id {
            player = AVPlayer(url: url)
            let iv = CMTime(seconds: 1, preferredTimescale: 600)
            timeObserver = player?.addPeriodicTimeObserver(forInterval: iv, queue: .main) { [weak self] t in
                book.currentPosition = t.seconds
                if let d = self?.player?.currentItem?.duration, d.isNumeric { book.duration = d.seconds }
            }
        }
        player?.seek(to: CMTime(seconds: book.currentPosition, preferredTimescale: 600))
        player?.play(); isPlaying = true; currentBook = book
        MPNowPlayingInfoCenter.default().nowPlayingInfo = [
            MPMediaItemPropertyTitle: book.title,
            MPMediaItemPropertyArtist: book.author,
            MPNowPlayingInfoPropertyElapsedPlaybackTime: book.currentPosition,
            MPMediaItemPropertyPlaybackDuration: book.duration
        ]
    }
    func addBookmark() {
        guard let book = currentBook, let pos = player?.currentTime().seconds else { return }
        book.bookmarks.append(Bookmark(position: pos))
    }
    func pause() { player?.pause(); isPlaying = false }
    func skip(_ s: Double) {
        guard let cur = player?.currentTime().seconds else { return }
        player?.seek(to: CMTime(seconds: cur + s, preferredTimescale: 600))
    }
    func seek(to s: Double) { player?.seek(to: CMTime(seconds: s, preferredTimescale: 600)) }
}

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN"
  "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
  <key>NSPrivacyTracking</key><false/>
  <key>NSPrivacyTrackingDomains</key><array/>
  <key>NSPrivacyCollectedDataTypes</key><array/>
  <key>NSPrivacyAccessedAPITypes</key>
  <array>
    <dict>
      <key>NSPrivacyAccessedAPIType</key>
      <string>NSPrivacyAccessedAPICategoryFileTimestamp</string>
      <key>NSPrivacyAccessedAPITypeReasons</key>
      <array>
        <string>C617.1</string>
      </array>
    </dict>
  </array>
</dict>
</plist>