修改代码同时播放和下载mp3，不下载mp3然后在Swift/SwiftUI中播放

Question

我已经创建了这段代码来播放/停止/倒回曲目，这些曲目将在设备上下载并存储在缓存中。 唯一的问题是它仅在曲目完全下载后才开始播放。 在此之前，应用程序完全冻结。 小型 mp3 没有问题，但如果是 30 分钟的音频怎么办？ 我需要修改此代码以立即开始播放音频并在后台下载曲目。 在这里寻求帮助，因为没有指南如何使用 AVAudioPlayer 来完成。 谢谢。

import Foundation
import AVFoundation
import AVFAudio

final class AudioManager: ObservableObject {
    
    // static let shared = AudioManager()
    
    var player: AVAudioPlayer?
    @Published private(set) var isDownloading = false
    @Published private(set) var isPlaying: Bool = false {
        didSet {
            print(isPlaying, "isPlaying")
        }
    }
    @Published private(set) var isLooping: Bool = false
    
    @MainActor func startPlayer(track: String) async {
        
        guard let fileURL = URL(string: track) else { return  }
        
        do {
            
            try AVAudioSession.sharedInstance().setCategory(.playback, mode: .default)
            try AVAudioSession.sharedInstance().setActive(true)
            
            
            let songName = fileURL.lastPathComponent
            var soundData: Data
            let tracksFolderUrl = FileManager.default.urls(for: .cachesDirectory, in: .userDomainMask).last!.appendingPathComponent("tracks")
            let trackUrl = tracksFolderUrl.appendingPathComponent(songName)
            
            if FileManager.default.fileExists(atPath: trackUrl.path) {
                // Load local data if it exists
                print("Loading data from \(trackUrl)")
                soundData = try Data(contentsOf: trackUrl)
            } else {
                
                //… otherwise load from network
                isDownloading = true
                print("Downloading data from \(fileURL)")
                (soundData, _) = try await URLSession.shared.data(from: fileURL)
                
                //… then save to disk
                try FileManager.default.createDirectory(at: tracksFolderUrl, withIntermediateDirectories: true)
                print("Saving data to \(trackUrl)")
                try soundData.write(to: trackUrl)
                isDownloading = false
            }
            
            self.player = try AVAudioPlayer(data: soundData)
            guard let player = player else { return }
            player.prepareToPlay()
            player.play()
            isPlaying = true
        }
        catch {
            
            print(error)
            
        }
    }
    
    func playPause() {
        
        guard let player = player else {
            print("Audio player not found")
            return
        }
        
        if player.isPlaying {
            player.pause()
            isPlaying = false

        } else {
            player.play()
            isPlaying = true

        }
        
    }
    
    func stop() {
        guard let player = player else {
            print("Audio player not found")
            return
        }
        
        if player.isPlaying {
            player.stop()
            isPlaying = false
        }
        
    }
    
    func toggleLoop() {
        guard let player = player else { return }
        
        player.numberOfLoops = player.numberOfLoops == 0 ? -1 : 0
        isLooping = player.numberOfLoops != 0
        print("isLooping", isLooping)
    }
    
}

Answer 1

您当前的代码将暂停

(soundData, _) = try await URLSession.shared.data(from: fileURL)

正在下载数据。

对于 stream 文件，使用 URL 初始化AVPlayer ：

AVPlayer(url: url)

如果您还想下载数据以保存在本地，您可以单独进行。

---

要获取曲目的持续时间：

player.currentItem?.duration

获取当前播放 position：

player.currentTime()

Apple 的文档在这里。