Flutter Local_Auth Setting for Android in Kotlin

localAuthSettingsForAndroid_kotlin.md

Note that local_auth plugin requires the use of a FragmentActivity as 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).

1. Add USE_FINGERPRINT permission

• Open android>app>src>main>AndroidManifest.xml
• Add the permission

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
          package="com.[your.package]">
  <uses-permission android:name="android.permission.USE_FINGERPRINT"/>
  <application...
    ...
    ...
    ...
<manifest>

2. Change FlutterActivity to FlutterFragmentActivity

If you receive this error: Exception has occurred. PlatformException (PlatformException(no_fragment_activity, local_auth plugin requires activity to be a FragmentActivity., null))

Then you need to do this step. Change FlutterActivity to FlutterFragmentActivity in MainActivity.kt.

package com.[your.package]

import androidx.annotation.NonNull;
import io.flutter.embedding.android.FlutterFragmentActivity
import io.flutter.embedding.engine.FlutterEngine
import io.flutter.plugins.GeneratedPluginRegistrant

class MainActivity: FlutterFragmentActivity() {
    override fun configureFlutterEngine(@NonNull flutterEngine: FlutterEngine) {
        GeneratedPluginRegistrant.registerWith(flutterEngine);
    }
}

3. Theme.AppCompat issue

If you receive this error: Exception has occurred. PlatformException (PlatformException(error, You need to use a Theme.AppCompat theme (or descendant) with this activity., null)) Then you need to do this:

1. Go to android>app>src>main>res>values>style.xml
2. Change the <style name="LaunchTheme" parent="@android:style/Theme.Black.NoTitleBar"> to <style name="LaunchTheme" parent="Theme.AppCompat.Light.NoActionBar">

---

ps: The local auth would not working if you update the Android Gradle Plugin.

@adminant I've faced this kind of issue before and found that the build Gradle version might be the culprit.

flutter/flutter#64996 (comment)

In my case throws 'Cannot resolve symbol 'Theme.AppCompat.Light.NoActionBar''

API 27 app crashes on trying to call biometrics with error

java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity.

thank you so much its working for me 100%

WORKED 100%

On the off chance that someone is still having issues after switching to a Theme.AppCompat, try also adding android:theme="@style/LaunchTheme" to your <application ... >

    <application
        android:name="${applicationName}"
        android:theme="@style/LaunchTheme"
        ...
       >