Custom NSURLProtocol with NSURLSession - ios

Question

I'm trying to implement this tutorial which implements a custom NSURLProtocol with NSURLConnection.
https://www.raywenderlich.com/76735/using-nsurlprotocol-swift
It works as expected, but now that NSURLConnection is deprecated in iOS9, I'm trying to convert it to NSURLSession.
Unfortunatly it didn't work.
I'm loading a website in uiwebview, if I use NSURLConnection it loads and everything work as expected, all http requests from the webview is captured, but not when using NSURLSession.
Any help is appreciated.
here is my code
import UIKit
class MyProtocol: NSURLProtocol, NSURLSessionDataDelegate, NSURLSessionTaskDelegate, NSURLSessionDelegate {
//var connection: NSURLConnection!
var mutableData: NSMutableData!
var response: NSURLResponse!
var dataSession: NSURLSessionDataTask!
override class func canInitWithRequest(request: NSURLRequest) -> Bool {
if NSURLProtocol.propertyForKey("MyURLProtocolHandledKey", inRequest: request) != nil {
return false
}
return true
}
override class func canonicalRequestForRequest(request: NSURLRequest) -> NSURLRequest {
return request
}
override class func requestIsCacheEquivalent(aRequest: NSURLRequest,
toRequest bRequest: NSURLRequest) -> Bool {
return super.requestIsCacheEquivalent(aRequest, toRequest:bRequest)
}
override func startLoading() {
let newRequest = self.request.mutableCopy() as! NSMutableURLRequest
NSURLProtocol.setProperty(true, forKey: "MyURLProtocolHandledKey", inRequest: newRequest)
self.dataSession = NSURLSession.sharedSession().dataTaskWithRequest(newRequest)
dataSession.resume()
self.mutableData = NSMutableData()
}
override func stopLoading() {
print("Data task stop")
self.dataSession.cancel()
self.mutableData = nil
}
func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask, didReceiveResponse response: NSURLResponse, completionHandler: (NSURLSessionResponseDisposition) -> Void) {
self.response = response
self.mutableData = NSMutableData()
print(mutableData)
}
func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask, didReceiveData data: NSData) {
self.client?.URLProtocol(self, didLoadData: data)
self.mutableData.appendData(data)
}
func URLSession(session: NSURLSession, task: NSURLSessionTask, didCompleteWithError error: NSError?) {
if (error == nil)
{
self.client!.URLProtocolDidFinishLoading(self)
self.saveCachedResponse()
}
else
{
self.client?.URLProtocol(self, didFailWithError: error!)
}
}
func saveCachedResponse () {
let timeStamp = NSDate()
let urlString = self.request.URL?.absoluteString
let dataString = NSString(data: self.mutableData, encoding: NSUTF8StringEncoding) as NSString?
print("TiemStamp:\(timeStamp)\nURL: \(urlString)\n\nDATA:\(dataString)\n\n")
}
}

Answer 1

I've solved it.
Here is the code if anyone needs it.
import Foundation
class MyProtocol1: NSURLProtocol, NSURLSessionDataDelegate, NSURLSessionTaskDelegate
{
private var dataTask:NSURLSessionDataTask?
private var urlResponse:NSURLResponse?
private var receivedData:NSMutableData?
class var CustomKey:String {
return "myCustomKey"
}
// MARK: NSURLProtocol
override class func canInitWithRequest(request: NSURLRequest) -> Bool {
if (NSURLProtocol.propertyForKey(MyProtocol1.CustomKey, inRequest: request) != nil) {
return false
}
return true
}
override class func canonicalRequestForRequest(request: NSURLRequest) -> NSURLRequest {
return request
}
override func startLoading() {
let newRequest = self.request.mutableCopy() as! NSMutableURLRequest
NSURLProtocol.setProperty("true", forKey: MyProtocol1.CustomKey, inRequest: newRequest)
let defaultConfigObj = NSURLSessionConfiguration.defaultSessionConfiguration()
let defaultSession = NSURLSession(configuration: defaultConfigObj, delegate: self, delegateQueue: nil)
self.dataTask = defaultSession.dataTaskWithRequest(newRequest)
self.dataTask!.resume()
}
override func stopLoading() {
self.dataTask?.cancel()
self.dataTask = nil
self.receivedData = nil
self.urlResponse = nil
}
// MARK: NSURLSessionDataDelegate
func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask,
didReceiveResponse response: NSURLResponse,
completionHandler: (NSURLSessionResponseDisposition) -> Void) {
self.client?.URLProtocol(self, didReceiveResponse: response, cacheStoragePolicy: .NotAllowed)
self.urlResponse = response
self.receivedData = NSMutableData()
completionHandler(.Allow)
}
func URLSession(session: NSURLSession, dataTask: NSURLSessionDataTask, didReceiveData data: NSData) {
self.client?.URLProtocol(self, didLoadData: data)
self.receivedData?.appendData(data)
}
// MARK: NSURLSessionTaskDelegate
func URLSession(session: NSURLSession, task: NSURLSessionTask, didCompleteWithError error: NSError?) {
if error != nil && error!.code != NSURLErrorCancelled {
self.client?.URLProtocol(self, didFailWithError: error!)
} else {
saveCachedResponse()
self.client?.URLProtocolDidFinishLoading(self)
}
}
// MARK: Private methods
/**
Do whatever with the data here
*/
func saveCachedResponse () {
let timeStamp = NSDate()
let urlString = self.request.URL?.absoluteString
let dataString = NSString(data: self.receivedData!, encoding: NSUTF8StringEncoding) as NSString?
print("TimeStamp:\(timeStamp)\nURL: \(urlString)\n\nDATA:\(dataString)\n\n")
}
}

Answer 2

Swift 3 version:
// CustomURLProtocol.swift
class CustomURLProtocol: URLProtocol, URLSessionDataDelegate, URLSessionTaskDelegate {
private var dataTask: URLSessionDataTask?
private var urlResponse: URLResponse?
private var receivedData: NSMutableData?
class var CustomHeaderSet: String {
return "CustomHeaderSet"
}
// MARK: NSURLProtocol
override class func canInit(with request: URLRequest) -> Bool {
guard let host = request.url?.host, host == "your domain.com" else {
return false
}
if (URLProtocol.property(forKey: CustomURLProtocol.CustomHeaderSet, in: request as URLRequest) != nil) {
return false
}
return true
}
override class func canonicalRequest(for request: URLRequest) -> URLRequest {
return request
}
override func startLoading() {
let mutableRequest = NSMutableURLRequest.init(url: self.request.url!, cachePolicy: NSURLRequest.CachePolicy.useProtocolCachePolicy, timeoutInterval: 240.0)//self.request as! NSMutableURLRequest
//Add User Agent
var userAgentValueString = "myApp"
mutableRequest.setValue(userAgentValueString, forHTTPHeaderField: "User-Agent")
print(mutableRequest.allHTTPHeaderFields ?? "")
URLProtocol.setProperty("true", forKey: CustomURLProtocol.CustomHeaderSet, in: mutableRequest)
let defaultConfigObj = URLSessionConfiguration.default
let defaultSession = URLSession(configuration: defaultConfigObj, delegate: self, delegateQueue: nil)
self.dataTask = defaultSession.dataTask(with: mutableRequest as URLRequest)
self.dataTask!.resume()
}
override func stopLoading() {
self.dataTask?.cancel()
self.dataTask = nil
self.receivedData = nil
self.urlResponse = nil
}
// MARK: NSURLSessionDataDelegate
func urlSession(_ session: URLSession, dataTask: URLSessionDataTask,
didReceive response: URLResponse,
completionHandler: #escaping (URLSession.ResponseDisposition) -> Void) {
self.client?.urlProtocol(self, didReceive: response, cacheStoragePolicy: .notAllowed)
self.urlResponse = response
self.receivedData = NSMutableData()
completionHandler(.allow)
}
func urlSession(_ session: URLSession, dataTask: URLSessionDataTask, didReceive data: Data) {
self.client?.urlProtocol(self, didLoad: data as Data)
self.receivedData?.append(data as Data)
}
// MARK: NSURLSessionTaskDelegate
func urlSession(_ session: URLSession, task: URLSessionTask, didCompleteWithError error: Error?) {
if error != nil { //&& error.code != NSURLErrorCancelled {
self.client?.urlProtocol(self, didFailWithError: error!)
} else {
//saveCachedResponse()
self.client?.urlProtocolDidFinishLoading(self)
}
}
}

Answer 3

The problem you are having with your code is that you are using the the NSURLSession.sharedSession to contain your data task. By using the shared session, you are not able to change the session delegate so none of your delegate routines are going to be invoked.
You will need to create a custom session with your protocol established as the delegate for the session. Then, when asked to start loading you can create a data task in that session.

Answer 4

From the documentation of URLSession:
Important
The session object keeps a strong reference to the delegate until your app exits or explicitly invalidates the session. If you don’t invalidate the session, your app leaks memory until it exits.
Also:
Note
Be careful to not create more sessions than you need. For example, if you have several parts of your app that need a similarly configured session, create one session and share it among them.
So I would move the creation of the URLSession from the startLoading method to the URLProtocol subclass initializer:
class MyURLProtocol: URLProtocol, URLSessionDataDelegate,URLSessionTaskDelegate {
override init(request: URLRequest, cachedResponse: CachedURLResponse?, client: URLProtocolClient?) {
super.init(request: request, cachedResponse: cachedResponse, client: client)
defaultSession = URLSession(configuration: .default, delegate: self, delegateQueue: nil)
}
private var defaultSession: URLSession?