swift - Right way of determining internet speed in iOS 8

Question

I am following the below code which I copied and converted from a stack overflow question.

I am getting internet speed however I am not sure, If I am doing right thing.

import UIKit

class ViewController: UIViewController, NSURLConnectionDataDelegate{
var connection:NSURLConnection!
var length:Int!
var startTime:NSDate!

//let kMinimumMegabytesPerSecond: CGFloat = 1

let kMaximumElapsedTime: CGFloat = 2.0



override func viewDidLoad() {
    super.viewDidLoad()
    self.testDownloadSpeed()
    // Do any additional setup after loading the view, typically from a nib.
}

func testDownloadSpeed() {
    var url: NSURL = NSURL(string: "http://thewallpaperhost.com/wp-content/uploads/2014/12/wallpapers-hd-8000-8331-hd-wallpapers.jpg")!
    var request: NSURLRequest = NSURLRequest(URL: url)
    self.startTime = NSDate()
    self.length = 0
    self.connection = NSURLConnection(request: request, delegate: self)
    self.connection.start()
    let delayInSeconds:Int64 =  1000000000  * 2
    var popTime:dispatch_time_t = dispatch_time(DISPATCH_TIME_NOW, (Int64)(delayInSeconds ))
    dispatch_after(popTime, dispatch_get_main_queue(), {() -> Void in
       if let conn = self.connection {
            self.connection.cancel()
            self.connection = nil
            self.useOffline()
        }
    })
}

func determineMegabytesPerSecond() -> CGFloat {
    var elapsed: NSTimeInterval
    if (startTime != nil) {
        elapsed = NSDate().timeIntervalSinceDate(startTime)
        var d =  (Double(length) / elapsed)
        var result = CGFloat( d/1024)
        result = result * 0.0078125
        result = result * 0.0009765625
        return result

    }
    return -1
}

func useOnline() {
     NSLog("Successful")
     NSLog("(determineMegabytesPerSecond())")

}

func useOffline() {

    NSLog("UnSuccessful")
    NSLog("(determineMegabytesPerSecond())")
}

func connection(connection: NSURLConnection, didReceiveResponse response: NSURLResponse) {
    NSLog("data came")
    self.startTime = NSDate()
}


func connection(connection: NSURLConnection, didFailWithError error: NSError) {
    if let conn = self.connection {
        self.connection = nil
        useOffline()
    }
}


func connectionDidFinishLoading(connection: NSURLConnection) {
    self.connection = nil

    useOnline()
}

func connection(connection: NSURLConnection, didReceiveData data: NSData) {
    self.length  = self.length +  data.length
    NSLog("(data.length)")
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

}

I copied the code from below URL. It was in Objective C so I converted the code!

How to detect Network Signal Strength in iOS Reachability

Answer 1

You code snippet was taken from this answer. I've updated it to use NSURLSession. The Swift rendition is below:

class ViewController: UIViewController, NSURLSessionDelegate, NSURLSessionDataDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()

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

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

        let configuration = NSURLSessionConfiguration.ephemeralSessionConfiguration()
        configuration.timeoutIntervalForResource = timeout
        let session = NSURLSession(configuration: configuration, delegate: self, delegateQueue: nil)
        session.dataTaskWithURL(url).resume()
    }

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

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

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

}