App login with FirebaseUI - handle sign in results

applogin2.java

override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent) {
    super.onActivityResult(requestCode, resultCode, data)
    if (requestCode == RC_SIGN_IN) {
        val response = IdpResponse.fromResultIntent(data)
        if (resultCode == Activity.RESULT_OK) {
            // handle login
        }
    }
}