Reusable WordPress Admin Notices PHP class

wp-admin-notices.php

<?php
/**
 * source: http://wordpress.stackexchange.com/a/222027/3844
 *
 * USAGE:
 *  add_action('admin_notices', [AdminNotice::getInstance(), 'displayAdminNotice']);
 *  $notice = AdminNotice::getInstance();
 *  $notice->displayError(__('Better flee, an error occurred.', 'herp'));
 *
 */
class AdminNotice
{
    private static $instance;
    const NOTICE_FIELD = 'derp_admin_notice_message';

    protected function __construct() {}
    private function __clone() {}
    private function __wakeup() {}

    static function getInstance()
    {
        if (null === static::$instance) {
            static::$instance = new static();
        }

        return static::$instance;
    }

    public function displayAdminNotice()
    {
        $option      = get_option(self::NOTICE_FIELD);
        $message     = isset($option['message']) ? $option['message'] : false;
        $noticeLevel = ! empty($option['notice-level']) ? $option['notice-level'] : 'notice-error';

        if ($message) {
            echo "<div class='notice {$noticeLevel} is-dismissible'><p>{$message}</p></div>";
            delete_option(self::NOTICE_FIELD);
        }
    }

    public function displayError($message)
    {
        $this->updateOption($message, 'notice-error');
    }

    public function displayWarning($message)
    {
        $this->updateOption($message, 'notice-warning');
    }

    public function displayInfo($message)
    {
        $this->updateOption($message, 'notice-info');
    }

    public function displaySuccess($message)
    {
        $this->updateOption($message, 'notice-success');
    }

    protected function updateOption($message, $noticeLevel) {
        update_option(self::NOTICE_FIELD, [
            'message' => $message,
            'notice-level' => $noticeLevel
        ]);
    }
}