Tracking Webviews

A native app can display web content and delegate functionality to an embedded browser called a webview. To track events from a webview in the Tealium iOS or Android SDK you need a communication bridge to the native code. This is done using JavaScript to invoke native code by sending messages to your app.

This solution works in webviews with or without the Tealium Universal Tag (utag.js) installed.

How It Works

This solution uses the following components:

Webview JavaScript Handler
This JavaScript code is a wrapper around your web-based event tracking to send the events to the native app.
- With Tag Management - Use extensions to quickly add this code to your pages.
- Without Tealium - Use existing event tracking or add tracking to the pages.
Native Message Handler
This native code uses a JavaScript interface to receive the messages containing the event data.

Webview JavaScript Handler

The following JavaScript code provides two wrapper functions, one for tracking views and one for tracking events, to forward a web-based tracking call to the native code. This code works for iOS and Android.

function tealView(tealiumEvent, data) {
  if (!tealiumEvent) {
    return;
  }
  if (window.WebViewInterface) {
    window.WebViewInterface.trackView(tealiumEvent, JSON.stringify(data));
  } else if (window.webkit
      && window.webkit.messageHandlers
      && window.webkit.messageHandlers.tealium) {
    var message = {
      command: 'trackView',
      title: tealiumEvent,
      data: data
    };
    window.webkit.messageHandlers.tealium.postMessage(message);
  }
}

function tealEvent(tealiumEvent, data) {
  if (!tealiumEvent) {
    return;
  }
  if (window.WebViewInterface) {
    window.WebViewInterface.trackEvent(tealiumEvent, JSON.stringify(data));
  } else if (window.webkit
      && window.webkit.messageHandlers
      && window.webkit.messageHandlers.tealium) {
    var message = {
      command: 'track',
      title: tealiumEvent,
      data: data
    };
    window.webkit.messageHandlers.tealium.postMessage(message);
  }
}

Webview With Tealium

If the pages loaded in the webview already have the Tealium Universal Tag (utag.js), then add the JavaScript handler code using two JavaScript Code extensions: one to initialize the wrapper functions and one to forward existing tracking calls to the JavaScript interface.

In this scenario the webview pages and the native app must be using different Tag Management profiles.

Add the JavaScript handler code to a JavaScript Code extension scoped to Pre Loader.
Add the following code to a second JavaScript Code extension scoped to All Tags - After Tags. This forwards the existing Tealium tracking calls, already occuring in the webview, to the native host app.
```
if (a == "view") {
  tealView(b.tealium_event, b);
} else if (a == "link") {
  tealEvent(b.tealium_event, b);
}
```

Webview Without Tealium

If the pages loaded in the webview do not have Tealium, then add the JavaScript handler code to each page that loads inside a webview. Then call tealView to track page views and tealLink when a non-page view event occurs, such as a button click or cart event.

Native Message Handler

To invoke native Android code from JavaScript, implement a class with methods marked @JavaScriptInterface:

public class WebViewInterface {

    @JavascriptInterface
    public void trackView(String viewName, String data) throws JSONException {
	    tealium.track(viewName, new JSONObject(data));
    }

    @JavascriptInterface
    public void trackEvent(String eventName, String data) throws JSONException {
    	tealium.track(eventName, new JSONObject(data));
    }
}

Once the native interface is created, register it with your WebView to make it visible to JavaScript code running in the WebView.

mWebView.addJavascriptInterface(mInterface, "WebViewInterface");

Call the method addJavascriptInterface() prior to calling the webView.loadUrl() method. Also, due to security concerns, only add the JavaScriptInterface on API version JELLY_BEAN_MR1 and above.

Add the following message handler to the WebView’s user content controller:

webView.configuration.userContentController.add(self, name: "tealium")

To invoke native iOS code from JavaScript, create a message handler class conforming to the WKScriptMessageHandler protocol. For tracking, call Tealium.track inside the userContentController:didReceive: callback:

func userContentController(_ userContentController: WKUserContentController,
                          didReceive message: WKScriptMessage) {

  guard let body = message.body as? [String: Any],
      let command = body["command"] as? String,
      let title = body["title"] as? String,
      let webViewData = body["data"] as? [String: Any] else {
          return
  }

  switch command {
  case "track":
      TealiumHelper.shared.tealium?.track(title: title,
                                          data: webViewData,
                                          completion: nil)
  case "trackView":
      TealiumHelper.shared.tealium?.trackView(title: title,
                                              data: webViewData,
                                              completion: nil)
  default:
      break
  }
}

Supported Libraries

The following platforms support the JavaScript interface solution: