如何在多个ViewControllers中快速查看downloadTask的进度

// DownloadManager.swift

import Foundation

class DownloadManager: NSObject, URLSessionDownloadDelegate {
    static let shared = DownloadManager()
    
    private var downloadTask: URLSessionDownloadTask?
    private var downloadProgress: Float = 0.0
    
    private override init() {
        super.init()
    }
    
    func startDownload(url: URL) {
        let session = URLSession(configuration: .default, delegate: self, delegateQueue: nil)
        downloadTask = session.downloadTask(with: url)
        downloadTask?.resume()
    }
    
    func cancelDownload() {
        downloadTask?.cancel()
    }
    
    func getDownloadProgress() -> Float {
        return downloadProgress
    }
    
    // URLSessionDownloadDelegate methods
    
    func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
        // Handle downloaded file
    }
    
    func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) {
        downloadProgress = Float(totalBytesWritten) / Float(totalBytesExpectedToWrite)
    }
}

// ViewController.swift

import UIKit

class ViewController: UIViewController {
    @IBOutlet weak var progressView: UIProgressView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // Start download
        let downloadURL = URL(string: "https://example.com/file.zip")!
        DownloadManager.shared.startDownload(url: downloadURL)
        
        // Update progress
        Timer.scheduledTimer(withTimeInterval: 0.1, repeats: true) { [weak self] timer in
            guard let self = self else {
                timer.invalidate()
                return
            }
            
            let progress = DownloadManager.shared.getDownloadProgress()
            self.progressView.progress = progress
        }
    }
    
    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        
        // Cancel download when leaving the ViewController
        DownloadManager.shared.cancelDownload()
    }
}