[local_auth] Update README for Android Integration (#3348)

Author: ditman

packages/local_auth/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.0.0-nullsafety.1
+
+* Update README for Android Integration.
+
 ## 1.0.0-nullsafety
 
 * Migrate to null safety.
@@ -182,4 +186,4 @@
 
 ## 0.0.1
 
-* Initial release of local authentication plugin.
+* Initial release of local authentication plugin.

packages/local_auth/README.md

@@ -142,6 +142,42 @@ opposed to Activity. This can be easily done by switching to use
 `FlutterFragmentActivity` as opposed to `FlutterActivity` in your
 manifest (or your own Activity class if you are extending the base class).
 
+Update your MainActivity.java:
+
+```java
+import android.os.Bundle;
+import io.flutter.app.FlutterFragmentActivity;
+import io.flutter.plugins.flutter_plugin_android_lifecycle.FlutterAndroidLifecyclePlugin;
+import io.flutter.plugins.localauth.LocalAuthPlugin;
+
+public class MainActivity extends FlutterFragmentActivity {
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        FlutterAndroidLifecyclePlugin.registerWith(
+                registrarFor(
+                        "io.flutter.plugins.flutter_plugin_android_lifecycle.FlutterAndroidLifecyclePlugin"));
+        LocalAuthPlugin.registerWith(registrarFor("io.flutter.plugins.localauth.LocalAuthPlugin"));
+    }
+}
+```
+
+OR
+
+Update your MainActivity.kt:
+
+```kotlin
+import io.flutter.embedding.android.FlutterFragmentActivity
+import io.flutter.embedding.engine.FlutterEngine
+import io.flutter.plugins.GeneratedPluginRegistrant
+
+class MainActivity: FlutterFragmentActivity() {
+    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
+        GeneratedPluginRegistrant.registerWith(flutterEngine)
+    }
+}
+```
+
 Update your project's `AndroidManifest.xml` file to include the
 `USE_FINGERPRINT` permissions:
 
@@ -172,4 +208,4 @@ app resumes.
 For help getting started with Flutter, view our online
 [documentation](http://flutter.io/).
 
-For help on editing plugin code, view the [documentation](https://flutter.io/platform-plugins/#edit-code).
+For help on editing plugin code, view the [documentation](https://flutter.io/platform-plugins/#edit-code).

packages/local_auth/pubspec.yaml

@@ -2,7 +2,7 @@ name: local_auth
 description: Flutter plugin for Android and iOS device authentication sensors
   such as Fingerprint Reader and Touch ID.
 homepage: https://github.com/flutter/plugins/tree/master/packages/local_auth
-version: 1.0.0-nullsafety
+version: 1.0.0-nullsafety.1
 
 flutter:
   plugin: