如何让UIProgressView在swift中工作

Question

我正在尝试实现UIProgressView!。我正在从一个网站下载一些数据，我并没有把我的头围绕着一些如何编写这段代码的基本原理。我有一个名为message的标签，它将在数据下载时更新，但我想显示正在下载的数据的进度。

import UIKit
class ViewController: UIViewController {
    //They user types in the city they want to recieve the weather from
    @IBOutlet weak var city: UITextField!
    //The label that is being updated when the data finally reaches the phone
    @IBOutlet weak var message: UILabel!
    //The progress bar
    @IBOutlet weak var downloadProgress: UIProgressView!
    //My 'What's the weather?' button
    @IBAction func buttonPressed(sender: AnyObject) {
        //When you touch the button, the keyboard goes away
        self.view.endEditing(true)
        //setting the urlString to the address of the website, it will add the city that you type into the city text field
        var urlString = "http://www.weather-forecast.com/locations/" + city.text.stringByReplacingOccurrencesOfString(" ", withString: "") + "/forecasts/latest"
        //Setting the url to the urlString
        var url = NSURL(string: urlString)
        let task = NSURLSession.sharedSession().dataTaskWithURL(url!){(data, response, error) in
            var urlContent = NSString(data: data, encoding: NSUTF8StringEncoding) 
            var contentArray  = urlContent!.componentsSeparatedByString("<span class="phrase">")
            var newContentArray = contentArray[1].componentsSeparatedByString("</span>")
            //Updating the message text with the content that I want from the HTML source
            self.message.text = (newContentArray[0] as! String) 
        }
        task.resume()
    }
    override func viewDidLoad() {
        super.viewDidLoad()
self.downloadProgress.progress = 0.0
    }
    func makeMyProgressBarMoving {
        var recievedData : Float
        var expectedTotalSize : Float
        var actual : Float = downloadProgress.progress
        if (actual < 1) {
            downloadProgress.progress = actual + (recievedData/expectedTotalSize)
            [NSTimer .scheduledTimerWithTimeInterval(0.05, invocation: self, repeats: false)]
        }   
    }

Answer 1

您无法更新进度，因为您没有拥有任何进度。您实现了错误的下载数据的方式。用另一种方式，你获得委托消息的方式。其中一个告诉你进度。特别是，您将实现

func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask, didReceiveData data: NSData {

这里你将在NSMutableData中积累数据，每次，你都可以将积累数据的大小与预期的总数据的大小进行比较，因此你有更新UIProgressView的基础。