get progress from dataTaskWithURL in swift

Question

Is there any way to get progress from dataTaskWithURL in swift while the data is downloading?

NSURLSession.sharedSession().dataTaskWithURL(...)         


        

Answer 1

In reference to Dharmesh's work, there have been quite a number of minor changes with URLSessionDelegate and URLSessionDataDelegate delegate methods. Here come the code for Swift 4.2 compatibility.

import UIKit

class ViewController: UIViewController, URLSessionDelegate, URLSessionDataDelegate {
    // MARK: - Variables

    // MARK: - IBOutlet
    @IBOutlet weak var progress: UIProgressView!

    // MARK: - IBAction
    @IBAction func goTapped(_ sender: UIButton) {
        let url = URL(string: "http://www.example.com/file.zip")!
        fetchFile(url: url)
    }

    // MARK: - Life cycle
    override func viewDidLoad() {
        super.viewDidLoad()
    }

    func fetchFile(url: URL) {
        progress.progress = 0.0
        let configuration = URLSessionConfiguration.default
        let mainQueue = OperationQueue.main
        session = URLSession(configuration: configuration, delegate: self, delegateQueue: mainQueue)
        dataTask = session?.dataTask(with: URLRequest(url: url))
        dataTask?.resume()
    }

    var buffer: NSMutableData = NSMutableData()
    var session: URLSession?
    var dataTask: URLSessionDataTask?
    var expectedContentLength = 0

    func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive data: Data) {
        buffer.append(data)
        let percentageDownloaded = Float(buffer.length) / Float(expectedContentLength)
        progress.progress =  percentageDownloaded
    }

    func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive response: URLResponse, completionHandler: (URLSession.ResponseDisposition) -> Void) {
        expectedContentLength = Int(response.expectedContentLength)
        completionHandler(URLSession.ResponseDisposition.allow)
    }

    func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
        progress.progress = 1.0
    }
}