自定义 NSURLProtocol 与 NSURLSession

Question

我正在尝试实施本教程，该教程使用 NSURLConnection 实施自定义 NSURLProtocol。

https://www.raywenderlich.com/76735/using-nsurlprotocol-swift

它按预期工作，但现在 NSURLConnection 在 iOS9 中已弃用，我正在尝试将其转换为 NSURLSession。

不幸的是，它没有用。

我正在 uiwebview 中加载一个网站，如果我使用 NSURLConnection 它加载并且一切都按预期工作，来自 webview 的所有 http 请求都会被捕获，但在使用 NSURLSession 时不会。

感谢任何帮助。

这是我的代码

    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

您的代码遇到的问题是您使用 NSURLSession.sharedSession 来包含数据任务。通过使用共享会话，您无法更改会话委托，因此 none 的委托例程将被调用。

您将需要创建一个自定义会话，并将您的协议建立为会话的委托。然后，当要求开始加载时，您可以在该会话中创建数据任务。

Answer 2

我已经解决了

如果有人需要的话，这是代码。

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 3

Swift 3 版本：

//  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 4

来自 URLSession 的文档：

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.

另外：

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.

所以我会将 URLSession 的创建从 startLoading 方法移动到 URLProtocol 子类初始值设定项：

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?

自定义 NSURLProtocol 与 NSURLSession

Custom NSURLProtocol with NSURLSession

nsurlprotocol

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nsurlsession

swift

nsurlsessiondatatask