public function actionSignup(){
    if(!Yii::$app->user->isGuest){
        return $this->goHome();
    }
    $model = new signupForm();
    if($model->load(Yii::$app->request->post()) && $model->validate()){
        $user = new User();
        $user->username = $model->username;
        $user->password = $user->setPassword($model->password);//Yii::$app->security->generatePasswordHash($model->password);//
        if($user->save() && Yii::$app->user->login($user->findByUsername($user->username), $this->rememberMe ? 3600*24*30 : 0)){
            return $this->goHome();
        } else {
            return $user->error;
        }

    }
    return $this->render('signup', ['model' => $model] );
}

public function actionLogin(){
       if (!Yii::$app->user->isGuest){
            return $this->goHome();
        }

        $model = new LoginForm();
        if ($model->load(Yii::$app->request->post()) && $model->login()){
                return $this->goBack();
            }

        $model->password = '';
        return $this->render('login', [
            'model' => $model,
        ]);
    }

<?php

namespace appmodels;

use Yii;
use yiibaseModel;
use appmodelsUser;


class LoginForm extends Model{
    public $username;
    public $password;
    public $rememberMe = true;

    private $_user = false;


    public function rules(){
        return [
            // username and password are both required
            [['username', 'password'], 'required'],
            // rememberMe must be a boolean value
            ['rememberMe', 'boolean'],
            // password is validated by validatePassword()
            ['password', 'validatePassword'],
        ];
    }

   public function attributeLabels() {
       return [
       'username' => 'Имя',
       'password' => 'Пароль',
       'rememberMe' => 'Запомнить меня',
     ];
   }

    public function validatePassword($attribute, $params){

        if (!$this->hasErrors()) {
            $user = $this->username;
            if($lol = $this->getUser($user)){
                if(!$lol || !$lol->validatePassword($this->password, $lol->password_hash )){
                    $this->addError($attribute, 'Неправильный пароль');
                } else {
                    return true;
                }
            } else {
                $this->addError($attribute, 'Такого логина не существует.');
            }
        }
     }

    public function login(){
        if ($this->validate()){
            return Yii::$app->user->login($this->getUser(), $this->rememberMe ? 3600*24*30 : 0);
        }
        return false;
    }


    public function getUser(){
        if ($this->_user === false) {
            $this->_user = User::findByUsername($this->username);
        }

        return $this->_user;
    }

}