title: how to add one or more plugins to an existing app
body: <p>My company want to make an application which like a bookshelf can load more books when the application finished, they want the application to be able to load more plugins without destroying the already installed code: when the app has been purchased and downloaded from the app store, the user can buy plugins in the app store and install them into the app. </p>
  
  <p>Can anyone tell me how this could be achieved? Thank you very much.</p>