Apple's iOS developer guidelines state:
3.3.2 — An Application may not itself install or launch other executable code by any means, including without limitation through the use of a plug-in architecture, calling other frameworks, other APIs or otherwise. No interpreted code may be downloaded or used in an Application except for code that is interpreted and run by Apple’s Documented APIs and built-in interpreter(s).
Assuming that downloading data - like XML and images (or a game level description), for example - at run-time is allowed (as is my impression), I am wondering where they draw the line between "data" and "code". Picture the scenario of an app that delivers interactive "presentations" to users (like a survey, for instance). Presentations are added continuously to the server and different presentations are made available to different users, so they cannot be part of the initial app download (this is the whole point). They are described in XML format, but being interactive, they might contain conditional branching of this sort (shown in pseudo form to exemplify):
<options id="Gender">
<option value="1">Male</option>
<option value="2">Female</option>
</options>
<branches id="Gender">
<branch value="1">
<image src="Man" />
</branch>
<branch value="2">
<image src="Woman" />
</branch>
</branches>
When the presentation is "played" within the app, the above would be presented in two steps. First a selection screen where the user can click on either of the two choices presented ("Male" or "Female"). Next, an image will be [downloaded dynamically] and displayed based on the choice made in the previous step.
Now, it's easy to imagine additional tags describing further logic still. For example, a containing tag could be added:
<loop count="3">
<options... />
<branches... />
</loop>
The result here being that the selection screen / image screen pair would be sequentially presented three times over, of course.
Or imagine some description of a level in a game. It's easy to view that as passive "data", but if it includes, say, several doorways that the user can go through and with various triggers, traps and points attached to them etc - isn't that the same as using a script - or, indeed, interpreted code - to describe options and their conditional responses?
Assuming that the interpretation engine for this XML data is already present in the app and that such presentations can only be consumed (not created or edited) in the app, how would this fare against Apple's iOS guidelines? Doesn't XML basically constitute a scripting language (couldn't any interpreted programming language simply be described by XML) in this sense?
Would it be OK if the proprietary scripting language (ref the XML used above) was strictly sandboxed (how can they tell?) and not given access to the operating system in any way (but able to download content dynamically - and upload results to the authoring server)?
Where does the line go?
