as you know there is a mobile support for plugin page in documentation and there is a example named certificate activity module there, i passed every step exactly by page but i couldn't see any changes on my mobile app? where is wrong? as i understand the plugin should add a new menu option,isn't it?
the certificate plugin doesn't add a new option to the main menu. This plugin supports the Certificate activity in the Mobile app, so if you add a certificate to your course you should be able to view it in the Mobile app.
To add new options to the main menu you need to use CoreMainMenuDelegate in the "delegate" field of mobile.php (you can see the list of delegates in here). Please notice that your plugin will appear in the "More" page, you cannot add a plugin to the bottom tabs.