无法在 Swift 中创建 URLSession 实例

Question

我想看看下载需要多长时间，我看到了这个link on how to do it ，所以我稍微调整了一下（例如更改重命名类等）以在 Swift 3 中工作。但是，我有一个问题：let session = URLSession(configuration: configuration, delegate: self, delegateQueue: nil) 我无法修复，并且此错误消息不断弹出：

Argument labels '(configuration:, delegate:, delegateQueue:)' do not match any available overloads

这是我的代码：（有问题的行是以下一行 // ISSUE ON NEXT LINE）

import UIKit

class ViewController: UIViewController, URLSessionDelegate, URLSessionDataDelegate {

override func viewDidLoad() {
    super.viewDidLoad()

    testDownloadSpeedWithTimout(timeout: 5.0) { (megabytesPerSecond, error) -> () in
        print("\(megabytesPerSecond); \(error)")
    }
}

var startTime: CFAbsoluteTime!
var stopTime: CFAbsoluteTime!
var bytesReceived: Int!
var speedTestCompletionHandler: ((_ megabytesPerSecond: Double?, _ error: NSError?) -> ())!

/// Test speed of download
///
/// Test the speed of a connection by downloading some predetermined resource. Alternatively, you could add the
/// URL of what to use for testing the connection as a parameter to this method.
///
/// - parameter timeout:             The maximum amount of time for the request.
/// - parameter completionHandler:   The block to be called when the request finishes (or times out).
///                                  The error parameter to this closure indicates whether there was an error downloading
///                                  the resource (other than timeout).
///
/// - note:                          Note, the timeout parameter doesn't have to be enough to download the entire
///                                  resource, but rather just sufficiently long enough to measure the speed of the download.

func testDownloadSpeedWithTimout(timeout: TimeInterval, completionHandler:@escaping (_ megabytesPerSecond: Double?, _ error: NSError?) -> ()) {
    let url = NSURL(string: "http://insert.your.site.here/yourfile")!

    startTime = CFAbsoluteTimeGetCurrent()
    stopTime = startTime
    bytesReceived = 0
    speedTestCompletionHandler = completionHandler

    let configuration = URLSessionConfiguration.ephemeral
    configuration.timeoutIntervalForResource = timeout

    ////////////////// ISSUE ON NEXT LINE ///////////////////

    let session = URLSession(configuration: configuration, delegate: self, delegateQueue: nil)
    session.dataTaskWithURL(url).resume()
}

func URLSession(session: URLSession, dataTask: URLSessionDataTask, didReceiveData data: NSData) {
    bytesReceived! += data.length
    stopTime = CFAbsoluteTimeGetCurrent()
}

func URLSession(session: URLSession, task: URLSessionTask, didCompleteWithError error: NSError?) {
    let elapsed = stopTime - startTime
    guard elapsed != 0 && (error == nil || (error?.domain == NSURLErrorDomain && error?.code == NSURLErrorTimedOut)) else {
        speedTestCompletionHandler?(nil, error)
        return
    }

    let speed = elapsed != 0 ? Double(bytesReceived) / elapsed / 1024.0 / 1024.0 : -1
    speedTestCompletionHandler?(speed, nil)
}

}

谁能告诉我这里有什么问题吗？我已经被困了很长一段时间了。谢谢！

Answer 1

检查下面更正后的代码

import UIKit

/* check delegate changes */

class ViewController: UIViewController, URLSessionTaskDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()

        testDownloadSpeedWithTimout(timeout: 5.0) { (megabytesPerSecond, error) -> () in
            print("\(megabytesPerSecond); \(error)")
        }
    }

    var startTime: CFAbsoluteTime!
    var stopTime: CFAbsoluteTime!
    var bytesReceived: Int!
    var speedTestCompletionHandler: ((_ megabytesPerSecond: Double?, _ error: NSError?) -> ())!

    /// Test speed of download
    ///
    /// Test the speed of a connection by downloading some predetermined resource. Alternatively, you could add the
    /// URL of what to use for testing the connection as a parameter to this method.
    ///
    /// - parameter timeout:             The maximum amount of time for the request.
    /// - parameter completionHandler:   The block to be called when the request finishes (or times out).
    ///                                  The error parameter to this closure indicates whether there was an error downloading
    ///                                  the resource (other than timeout).
    ///
    /// - note:                          Note, the timeout parameter doesn't have to be enough to download the entire
    ///                                  resource, but rather just sufficiently long enough to measure the speed of the download.

    func testDownloadSpeedWithTimout(timeout: TimeInterval, completionHandler:@escaping (_ megabytesPerSecond: Double?, _ error: NSError?) -> ()) {

        let url = URL(string: "http://insert.your.site.here/yourfile")!

        startTime = CFAbsoluteTimeGetCurrent()
        stopTime = startTime
        bytesReceived = 0
        speedTestCompletionHandler = completionHandler

        let configuration = URLSessionConfiguration.ephemeral
        configuration.timeoutIntervalForResource = timeout

        ////////////////// ISSUE ON NEXT LINE IS NOW RESOLVED///////////////////

        let session = URLSession(configuration: configuration, delegate: self, delegateQueue: nil)
        session.dataTask(with: url).resume()
    }

    /* changes is below */

    func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive data: Data) {
        bytesReceived! += data.count
        stopTime = CFAbsoluteTimeGetCurrent()
    }

    func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
        let elapsed = stopTime - startTime

        guard let nserror = error as? NSError, elapsed != 0 && (nserror.domain == NSURLErrorDomain && nserror.code == NSURLErrorTimedOut) else {
            speedTestCompletionHandler?(nil, error as? NSError)
            return
        }

        let speed = elapsed != 0 ? Double(bytesReceived) / elapsed / 1024.0 / 1024.0 : -1
        speedTestCompletionHandler?(speed, nil)
    }

   /* changes end */

}

无法在 Swift 中创建 URLSession 实例

Unable to create an instance of URLSession in Swift

ios

nsurlsession

swift