Added a callback to the ui instance

Author: Nicolas Garnier

README.md

@@ -134,6 +134,26 @@ class SignInScreen extends React.Component {
 }
 ```
 
+### Accessing the FirebaseUI instance
+
+To allow for further configuration you can access the firebaseUI instance before it is started.
+To do this you can pass a `uiCallback` callback function that wil be passed the Firebase UI instance. For example here is how to enable the `disableAutoSignIn()` option:
+
+```js
+// ...
+
+render() {
+  return (
+    <div>
+      <h1>My App</h1>
+      <p>Please sign-in:</p>
+      <FirebaseAuth uiCallback={ui => ui.disableAutoSignIn()} uiConfig={this.uiConfig} firebaseAuth={firebase.auth()}/>
+    </div>
+  );
+}
+```
+
+
 ## Packing your app
 
 The `FirebaseAuth` component needs a global CSS to get proper styling. The CSS is already imported within `FirebaseAuth`.

src/FirebaseAuth.jsx

@@ -53,6 +53,9 @@ export default class FirebaseAuth extends React.Component {
     if (this.uiConfig.signInFlow === 'popup') {
       this.firebaseUiWidget.reset();
     }
+    if (this.uiCallback) {
+      this.uiCallback(this.firebaseUiWidget);
+    }
     this.firebaseUiWidget.start('#' + this.elementId, this.uiConfig);
   }
 
@@ -67,11 +70,18 @@ export default class FirebaseAuth extends React.Component {
    * Properties types.
    */
   props: {
-    uiConfig: Object, // The Firebase UI Web UI Config object.
-                      // See: https://github.com/firebase/firebaseui-web#configuration
-    firebaseAuth: Object, // The Firebase App auth instance to use.
-    elementId?: String, // The ID of the underlying container that we'll generate.
-                        // Use this if you use more than one instance at a time in your app.
+    // The Firebase UI Web UI Config object.
+    // See: https://github.com/firebase/firebaseui-web#configuration
+    uiConfig: Object,
+    // The Firebase App auth instance to use.
+    firebaseAuth: Object,
+    // The ID of the underlying container that we'll generate.
+    // Use this if you use more than one instance at a time in your app.
+    elementId?: String,
+    // Callback that will be passed the FirebaseUi instance before it is
+    // started. This allows access to certain configuration options such as
+    // disableAutoSignIn().
+    uiCallback?: Function,
     className: String
   };