does NSURLSession send user-agent automatically

Question

Does NSURLSession send user-agent automatically when user WatchKit 2.0, iOS 9.0? Is there a way to verify this within the WatchKit app?

Answer 1

Yes, a user agent is automatically provided as part of the default session configuration.

The default NSURLSession request header User-Agent field includes the Bundle Name (CFBundleName) and the Build Number (CFBundleVersion) of your watchOS app extension:

$(CFBundleName)/$(CFBundleVersion) CFNetwork/808.3 Darwin/16.3.0

Notice that your app's Version Number (CFBundleShortVersionString) isn't included. (See Technical Note TN2420: Version Numbers and Build Numbers for more info.)

For example, for product "Foo" with the Build Number 1, your user agent would be:

Foo%20WatchKit%20Extension/1 CFNetwork/808.3 Darwin/16.3.0

How to Verify?

I don't think there's a way within your app to examine the default user agent field, as it's nil (unless you've set it to a custom value).

But, you could use netcat to examine requests sent by the Simulator.

1. Run nc -l 5678 in Terminal to have netcat listen to requests sent to localhost on port 5678

2. In your app's Info.plist file, add the App Transport Security Settings dictionary with the Allow Arbitrary Loads key set to YES

3. Add the following code to the start of application(_:didFinishLaunchingWithOptions:)

   let url = URL(string: "http://localhost:5678/")!
   URLSession.shared.dataTask(with: url) { (data, response, error) in
       let body = String(data: data!, encoding: .utf8)!
       print("body: \(body)")
   }.resume()
   return true
   

4. Run your app in the Simulator and see what netcat outputs in Terminal

If your privacy is of no concern, you could use a service like user-agent.me to test on your device.

1. Replace localhost:5678 above with user-agent.me

2. Run your app on your device

3. Examine Xcode's Console output

When you're done verifying, remember to undo all of the changes above.

Answer 2

NSURLSession send User-Agent by default.
default User-Agent style like.

"User-Agent" = "UserAgentDemo/1 CFNetwork/1121.2.1 Darwin/19.2.0";

We can customize the User-Agent.

let config = URLSessionConfiguration.default
config.httpAdditionalHeaders = ["User-Agent": "zgpeace User-Agent"]

I write a demo for URLSession in the below.

     func requestUrlSessionAgent() {
        print("requestUrlSessionAgent")

        let config = URLSessionConfiguration.default
        // default User-Agent: "User-Agent" = "UserAgentDemo/1 CFNetwork/1121.2.1 Darwin/19.2.0";
        // custom User-Agent
        config.httpAdditionalHeaders = ["User-Agent": "zgpeace User-Agent"]
        let session = URLSession(configuration: config)

        let url = URL(string: "https://httpbin.org/anything")!
        var request = URLRequest(url: url)
        request.httpMethod = "GET"

        let task = session.dataTask(with: url) { data, response, error in

            // ensure there is no error for this HTTP response
            guard error == nil else {
                print ("error: \(error!)")
                return
            }

            // ensure there is data returned from this HTTP response
            guard let content = data else {
                print("No data")
                return
            }

            // serialise the data / NSData object into Dictionary [String : Any]
            guard let json = (try? JSONSerialization.jsonObject(with: content, options: JSONSerialization.ReadingOptions.mutableContainers)) as? [String: Any] else {
                print("Not containing JSON")
                return
            }

            print("gotten json response dictionary is \n \(json)")
            // update UI using the response here
        }

        // execute the HTTP request
        task.resume()

    }

By the way, the default User-Agent in WKWebView is different, like

Mozilla/5.0 (iPhone; CPU iPhone OS 13_3 like Mac OS X)

You can customize the WKWebView User-Agent

webView.customUserAgent = "zgpeace User-Agent"

I also write a demo for WKWebView:

func requestWebViewAgent() {
        print("requestWebViewAgent")

        let webView = WKWebView()
        webView.evaluateJavaScript("navigator.userAgent") { (userAgent, error) in
            if let ua = userAgent {
                print("default WebView User-Agent > \(ua)")
            }

            // customize User-Agent
            webView.customUserAgent = "zgpeace User-Agent"
        }
    }

Warning: "User-Agent" is nil from webView, when webView is released. You can set webView object as property to keep the webView.

NSURLConnection send User-Agent by default.
default User-Agent style like.

"User-Agent" = "UserAgentDemo/1 CFNetwork/1121.2.1 Darwin/19.2.0";

We can customize the User-Agent.

urlRequest.setValue("URLConnection zgpeace User-Agent", forHTTPHeaderField: "User-Agent")

I write a demo for URLConnection in the below.

func requestUrlConnectionUserAgent() {
    print("requestUrlConnectionUserAgent")

    let url = URL(string: "https://httpbin.org/anything")!
    var urlRequest = URLRequest(url: url)
    urlRequest.httpMethod = "GET"
    // default User-Agent: "User-Agent" = "UserAgentDemo/1 CFNetwork/1121.2.1 Darwin/19.2.0";
    urlRequest.setValue("URLConnection zgpeace User-Agent", forHTTPHeaderField: "User-Agent")

    NSURLConnection.sendAsynchronousRequest(urlRequest, queue: OperationQueue.main) { (response, data, error) in
        // ensure there is no error for this HTTP response
        guard error == nil else {
            print ("error: \(error!)")
            return
        }

        // ensure there is data returned from this HTTP response
        guard let content = data else {
            print("No data")
            return
        }

        // serialise the data / NSData object into Dictionary [String : Any]
        guard let json = (try? JSONSerialization.jsonObject(with: content, options: JSONSerialization.ReadingOptions.mutableContainers)) as? [String: Any] else {
            print("Not containing JSON")
            return
        }

        print("gotten json response dictionary is \n \(json)")
        // update UI using the response here
    }

  }

Demo in github:
https://github.com/zgpeace/UserAgentDemo.git

Answer 3

Related to your question, note that it is possible to manually set the User-Agent string for your NSURLSession in WatchKit, using a NSURLSessionConfiguration object and setting HTTPAdditionalHeaders.