As a reverse-engineer tinkering with iOS this reminded me of some system apps. E.g. in the app store you click a button, send a request, receive the response w

As a reverse-engineer tinkering with iOS this reminded me of some system apps. E.g. in the app store you click a button, send a request, receive the response which contains a xml-like structure describing the UI mutation to your action. <Alert> <Header>iTunes Login</Header> <Body>We could not find a user with those credentials.</Body> </Alert> type stuff.