src/System/Input.php
public static function isSsl()
    {
        $isSecure = false;
        if (isset($_SERVER['HTTPS']) && in_array($_SERVER['HTTPS'], ['on', '1'])) {
            $isSecure = true;
        } elseif (isset($_SERVER['HTTP_X_FORWARDED_PROTO']) && $_SERVER['HTTP_X_FORWARDED_PROTO'] == 'https') {
            $isSecure = true;
        } elseif (isset($_SERVER['HTTP_X_FORWARDED_SSL']) && $_SERVER['HTTP_X_FORWARDED_SSL'] == 'on') {
            $isSecure = true;
        }
        return $isSecure;
    }
public static function isSsl()
    {
        $isSecure = false;
        if (isset($_SERVER['HTTPS']) && in_array($_SERVER['HTTPS'], ['on', '1'])) {
            $isSecure = true;
        } elseif (isset($_SERVER['HTTP_X_FORWARDED_PROTO']) && $_SERVER['HTTP_X_FORWARDED_PROTO'] == 'https') {
            $isSecure = true;
        } elseif (isset($_SERVER['HTTP_X_FORWARDED_SSL']) && $_SERVER['HTTP_X_FORWARDED_SSL'] == 'on') {
            $isSecure = true;
        }
        return $isSecure;
    }
Is ssl.

@return boolean