yii2 retrieve passwordHash for AccessTokenByUser - yii2

Question

for use in Mobile App, I am trying to use Yii2 built in RestApi.
Now what I understand by the reading that we should disable session and set loginUrl property to false.
Now what I want is, I want a login screen for my app and want to authenticate against API.
how I can achieve the same.
Note:
I can authenticate with username and password for different controllers including users controller as well as bearer token.
also I read an example in" yii2 by example"
public function actionAccessTokenByUser($username, $passwordHash)
{
$accessToken = null;
$user = \app\models\User::findOne(['username' => $username, 'password_hash' => $passwordHash]);
//var_dump($passwordHash1);exit;
if($user!=null)
{
$user->access_token = Yii::$app->security->generateRandomString();
$user->save();
$accessToken = $user->access_token;
}
return [ 'access-token' => $accessToken ];
}
my question is how I get the `$passwordHash to supply here. I tried to look back and forth, but couldn't find any solution.
my main purpose is how I can implement a application login for mobile and thereon supply the accesstoken in the background wherever needed.

Answer 1

I believe I have refactored the code to achieve what I am looking. Open to suggestion or any flaw in my implementation.
here is what I have done.
public function actionAccessTokenByUser($username, $password)
{
$accessToken = null;
$username = \app\models\User::findByUsername($username);
if ($username!=null)
{
if($username->validatePassword($password)) $user = $username;
}
// $user = \app\models\User::findOne(['username' => $username, 'password_hash' => $passwordHash]);
if($user!=null)
{
$user->access_token = Yii::$app->security->generateRandomString();
$user->save();
$accessToken = $user->access_token;
}
return [ 'access-token' => $accessToken ];
}