react-navigation/docs/guides/Screen-Tracking.md
Mike Grabowski 26b165200f Add onNavigationStateChange (#453)
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2017-02-23 22:18:06 -08:00

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Screen tracking and analytics

This example shows how to do screen tracking and send to Google Analytics. The approach can be adapted to any other mobile analytics SDK.

Screen tracking

When using built-in navigation container, we can use onNavigationStateChange to track the screen.

import { GoogleAnalyticsTracker } from 'react-native-google-analytics-bridge';

const tracker = new GoogleAnalyticsTracker(GA_TRACKING_ID);

// gets the current screen from navigation state
function getCurrentScreen(navigationState) {
  if (!navigationState) {
    return null;
  }
  return navigationState.routes[navigationState.index].routeName;
}

const AppNavigator = StackNavigator(AppRouteConfigs);

export default () => (
  <AppNavigator
    onNavigationStateChange={(prevState, currentState) => {
      const currentScreen = getCurrentScreen(currentState);
      const prevScreen = getCurrentScreen(prevState);

      if (nextScreen !== currentScreen) {
        // the line below uses the Google Analytics tracker
        // change the tracker here to use other Mobile analytics SDK.
        tracker.trackScreenView(nextScreen);
      }
    }}
  />
);

Screen tracking with Redux

When using Redux, we can write a Redux middleware to track the screen. For this purpose, we will reuse getCurrentScreen from the previous section.

import { NavigationActions } from 'react-navigation';
import { GoogleAnalyticsTracker } from 'react-native-google-analytics-bridge';

const tracker = new GoogleAnalyticsTracker(GA_TRACKING_ID);

const screenTracking = ({ getState }) => next => (action) => {
  if (
    action.type !== NavigationActions.NAVIGATE
    && action.type !== NavigationActions.BACK
  ) {
    return next(action);
  }

  const currentScreen = getCurrentScreen(getState().navigation);
  const result = next(action);
  const nextScreen = getCurrentScreen(getState().navigation);
  if (nextScreen !== currentScreen) {
    // the line below uses the Google Analytics tracker
    // change the tracker here to use other Mobile analytics SDK.
    tracker.trackScreenView(nextScreen);
  }
  return result;
};

export default screenTracking;

Create Redux store and apply the above middleware

The screenTracking middleware can be applied to the store during its creation. See Redux Integration for details.

const store = createStore(
  combineReducers({
    navigation: navigationReducer,
    ...
  }),
  applyMiddleware(
    screenTracking,
    ...
    ),
);