Update analytics.md

Author: Ehesp

Diff for: docs/api/analytics.md

@@ -1 +1,88 @@
+# Analytics
 
+Integrating Firebase analytics is super simple using Firestack. A number of methods are provided to help tailor analytics specifically for your
+own app. The Firebase SDK includes a number of pre-set events which are automatically handled, and cannot be used with custom events:
+
+```
+  'app_clear_data',
+  'app_uninstall',
+  'app_update',
+  'error',
+  'first_open',
+  'in_app_purchase',
+  'notification_dismiss',
+  'notification_foreground',
+  'notification_open',
+  'notification_receive',
+  'os_update',
+  'session_start',
+  'user_engagement',
+```
+
+#### logEvent(event: string, params?: Object)
+
+Log a custom event with optional params. Returns a Promise.
+
+```javascript
+firestack.analytics()
+  .logEvent('clicked_advert', { id: 1337 })
+  .then(() => {
+    console.log('Event has been logged successfully'); 
+  });
+```
+
+#### setAnalyticsCollectionEnabled(enabled: boolean)
+
+Sets whether analytics collection is enabled for this app on this device.
+
+```javascript
+firestack.analytics()
+  .setAnalyticsCollectionEnabled(false);
+```
+
+#### setCurrentScreen(screenName: string, screenClassOverride: string)
+
+Sets the current screen name, which specifies the current visual context in your app.
+
+```javascript
+firestack.analytics()
+  .setCurrentScreen('user_profile');
+```
+
+#### setMinimumSessionDuration(miliseconds: number)
+
+Sets the minimum engagement time required before starting a session. The default value is 10000 (10 seconds).
+
+```javascript
+firestack.analytics()
+  .setMinimumSessionDuration(15000);
+```
+
+#### setSessionTimeoutDuration(miliseconds: number)
+
+Sets the duration of inactivity that terminates the current session. The default value is 1800000 (30 minutes).
+
+```javascript
+firestack.analytics()
+  .setSessionTimeoutDuration(900000);
+```
+
+#### setUserId(id: string)
+
+Gives a user a uniqiue identificaition.
+
+```javascript
+const id = firestack.auth().currentUser.uid;
+
+firestack.analytics()
+  .setUserId(id);
+```
+
+#### setUserProperty(name: string, value: string)
+
+Sets a key/value pair of data on the current user.
+
+```javascript
+firestack.analytics()
+  .setUserProperty('nickname', 'foobar');
+```