在 UITableviewCell 中显示下载进度

Question

我 iOS Developer.I 想要实现这样的功能，比如在 UITableview 中显示多个文件，文件名，UIProgressView 和下载 button.I 想要实现如果用户单击下载按钮然后开始下载文件并更新该单元格的 UIProgressView 值，如果我单击另一个单元格的下载按钮然后两个文件应该同时下载并显示下载状态。如果有人有想法请帮助我.这是我的代码

import UIKit

class PDFCell: UITableViewCell,URLSessionTaskDelegate,URLSessionDownloadDelegate {

    @IBOutlet weak var btnStartDownload: UIButton!
    @IBOutlet weak var downloadProgress: UIProgressView!
    var url:String?
    var percentageWritten: Float = 0.0
    var taskTotalBytesWritten = 0
    var taskTotalBytesExpectedToWrite = 0
    var task: URLSessionTask!
    let config = URLSessionConfiguration.background(withIdentifier: "lanet.PDFDownload")
    lazy var session: URLSession = {
        URLSession(configuration: config, delegate: self as! URLSessionDelegate, delegateQueue: OperationQueue())
    }()
    func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) {
        if totalBytesExpectedToWrite > 0 {
            let progress = Float(totalBytesWritten) / Float(totalBytesExpectedToWrite)
            DispatchQueue.main.async {
                self.downloadProgress.progress = progress
            }
            debugPrint("Progress \(downloadTask) \(progress)")
        }
    }
    override func prepareForReuse() {
        super.prepareForReuse()
        self.url = ""
    }
    func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
        let path = NSSearchPathForDirectoriesInDomains(FileManager.SearchPathDirectory.documentDirectory, FileManager.SearchPathDomainMask.userDomainMask, true)
        let documentDirectoryPath:String = path[0]
        let fileManager = FileManager()
        let destinationURLForFile = URL(fileURLWithPath: documentDirectoryPath.appendingFormat("/file.pdf"))
        if fileManager.fileExists(atPath: destinationURLForFile.path){
            // showFileWithPath(path: destinationURLForFile.path)
        }
        else{
            do {
                try fileManager.moveItem(at: location, to: destinationURLForFile)
                // show file
                // showFileWithPath(path: destinationURLForFile.path)
            }catch{
                print("An error occurred while moving file to destination url")
            }
        }

        debugPrint("Download finished: \(location)")
        try? FileManager.default.removeItem(at: location)
    }

    func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
        debugPrint("Task completed: \(task), error: \(error)")
    }


    override func awakeFromNib() {
        super.awakeFromNib()
        // Initialization code
    }

    override func setSelected(_ selected: Bool, animated: Bool) {
        super.setSelected(selected, animated: animated)

        // Configure the view for the selected state
    }

    @IBAction func btnDownloadClick(_ sender: Any) {
        let url = URL(string: self.url!)!
        let task = session.downloadTask(with: url)
        task.resume()
    }
}

}

Answer 1

阅读本教程以获取基本参考：https://www.raywenderlich.com/158106/urlsession-tutorial-getting-started

在下载进度部分您会看到

func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, 
  didWriteData bytesWritten: Int64, totalBytesWritten: Int64, 
  totalBytesExpectedToWrite: Int64) {
  // 1
  guard let url = downloadTask.originalRequest?.url,
    let download = downloadService.activeDownloads[url]  else { return }
  // 2
  download.progress = Float(totalBytesWritten) / Float(totalBytesExpectedToWrite)
  // 3
  let totalSize = ByteCountFormatter.string(fromByteCount: totalBytesExpectedToWrite, countStyle: .file)
  // 4
    DispatchQueue.main.async {
    if let trackCell = self.tableView.cellForRow(at: IndexPath(row: download.track.index,
      section: 0)) as? TrackCell {
      trackCell.updateDisplay(progress: download.progress, totalSize: totalSize)
    }
  }
}

在 UITableviewCell 中显示下载进度

Show download progress in UITableviewCell

uitableview

uiprogressview

ios

swift