Swift 3 and NSURLSession issue - swift3

Question

Thanks to Apple my iOS 9 Project 'Swift 2.3' is completely unusable with iOS 10's 'Swift 3'...
I fixed almost everything except that I am having issue with using NSURLSession, Xcode is telling me that it has been renamed to URLSession, if I rename it Xcode will tell me:
use of undeclared type URLSession
Foundation is imported.
What is the issue?!
For example I am using it this way...
lazy var defaultSession: URLSession = {
let configuration = URLSessionConfiguration.background(withIdentifier: "reCoded.BGDownload")
configuration.sessionSendsLaunchEvents = true
configuration.isDiscretionary = true
let session = URLSession(configuration: configuration, delegate: self, delegateQueue, queue: nil)
return session
}()
and even with the delegate methods the same issue.

Answer 1

Try using Foundation.URLSession where ever you use URLSession.

Answer 2

/Got it to work/ In some cases try to copy your code somewhere else then remove everything in your class that uses URLSession then type the session methods again and put back your copied code you should be fine.

Answer 3

Update your URLSessin functions with;
func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive data: Data) {
self.data.append(data as Data)
}
func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
if error != nil {
print("Failed to download data")
}else {
print("Data downloaded")
self.parseJSON()
}
}

Answer 4

I can explain how but by playing around with the code I got this to work in SWIFT 3 after two days of frustration. I guess SWIFT 3 removed a lot of unnecessary words.
let task = Foundation.URLSession.shared.dataTask(with: <#T##URL#>, completionHandler: <#T##(Data?, URLResponse?, Error?) -> Void#>)

Answer 5

Here's where I am right now. It's not perfect but works maybe half of the time.
First, in the class where my URLsession is defined:
import Foundation
class Central: NSObject, URLSessionDataDelegate, URLSessionDelegate, URLSessionTaskDelegate, URLSessionDownloadDelegate {
I don't think all of that is necessary, but there it is. Then here is the function that is called by my background fetch:
func getWebData() {
var defaults: UserDefaults = UserDefaults.standard
let backgroundConfigObject = URLSessionConfiguration.background(withIdentifier: "myBGconfig")
let backgroundSession = URLSession(configuration: backgroundConfigObject, delegate: self, delegateQueue: nil)
urlString = "https://www.powersmartpricing.org/psp/servlet?type=dayslider"
if let url = URL(string: urlString) {
let rateTask = backgroundSession.downloadTask(with: URL(string: urlString)!)
rateTask.taskDescription = "rate"
rateTask.resume()
}
When the task comes back:
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL ) {
if downloadTask.taskDescription == "rate" { // I run 2 web tasks during the session
if let data = NSData(contentsOf: location) {
var return1 = String(data: data as! Data, encoding: String.Encoding.utf8)!
DispatchQueue.global(qos: .userInteractive).asyncAfter(deadline: .now() + 0.2){
var defaults: UserDefaults = UserDefaults.standard
defaults.set(myNumber, forKey: "electricRate") // myNumber is an extract of the text in returned web data
defaults.set(Date(), forKey: "rateUpdate")
defaults.synchronize()
self.calcSetting() //Calls another function defined in the same class. That function sends the user a notification.
let notificationName = Notification.Name("GotWebData")
NotificationCenter.default.post(name: notificationName, object: nil)
} // Closes the Dispatch
}
if session.configuration.identifier == "myBGconfig" {
print("about to invalidate the session")
session.invalidateAndCancel()
}
}
I haven't figured out yet how to kill the session when BOTH tasks have completed, so right now I kill it when either one is complete, with invalidateAndCancel as above.
And finally, to catch errors:
func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didCompleteWithError: Error?) {
if downloadTask.taskDescription == "rate" {
print("rate download failed with error \(didCompleteWithError)")
}
if downloadTask.taskDescription == "other" {
print("other download failed with error \(didCompleteWithError)")
}
downloadTask.resume() // I'm hoping this retries if a task fails?
}
func urlSession(_ session: URLSession, didBecomeInvalidWithError error: Error?) {
if let error = error as? NSError {
print("invalidate, error %# / %d", error.domain, error.code)
} else {
print("invalidate, no error")
}
}