NSURLSessionDataDelegate not called

Question

I have been trying to implement the NSURLSessionDataDelegate, in particular to modify the cache policies that are in the HTTP Headers received in the response.

To do this I try to intercept the proposedResponse before it is cached by using the willCacheResponse method, but it does not get called.

I looked on this website and others but still I am not sure why the function willCacheResponse is not called.

Any ideas?

class ViewController: UIViewController, NSURLSessionDelegate, NSURLSessionDataDelegate, NSURLSessionTaskDelegate {

override func viewDidLoad() {
    super.viewDidLoad()

    let requestUrl = "https://www.google.com/data.json"
    let request = NSURLRequest(URL: NSURL(string: requestUrl)!)
    let configuration = NSURLSessionConfiguration.defaultSessionConfiguration()

    let session = NSURLSession(
        configuration: configuration,
        delegate: self,
        delegateQueue: NSOperationQueue.mainQueue()
    )

    let task = session.dataTaskWithRequest(request) {
        data, response, error in

        //print(data)
        print(response)
        //print(error)
    }
    task.resume()
}

func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask, willCacheResponse proposedResponse: NSCachedURLResponse, completionHandler: (NSCachedURLResponse?) -> Void) {
    print("willCacheResponse")
    completionHandler(proposedResponse)
}
}

Answer 1

class ViewController: UIViewController, NSURLSessionDelegate, NSURLSessionDataDelegate, NSURLSessionTaskDelegate {
    var session:NSURLSession!

    override func viewDidLoad() {
        super.viewDidLoad()

        let requestUrl = "https://www.google.com"
        let request = NSURLRequest(URL: NSURL(string: requestUrl)!)
        let configuration = NSURLSessionConfiguration.defaultSessionConfiguration()

        self.session = NSURLSession(
            configuration: configuration,
            delegate: self,
            delegateQueue: NSOperationQueue.mainQueue()
        )

        let task = session.dataTaskWithRequest(request)


        task.resume()
    }

    func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask, didReceiveData data: NSData) {
        print("Did receive data!")
    }

    func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask, didReceiveResponse response: NSURLResponse, completionHandler: (NSURLSessionResponseDisposition) -> Void) {
        print("Response!!")
    }
}