So I wouldn't be surprised if they react to that differently.

2.5.2 Apps should be self-contained in their bundles, and may not read or write data outside the designated container area, nor may they download, install, or execute code, including other iOS, watchOS, Mac OS X, or tvOS apps.

Older policy:

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).

Apple once prohibited a Commodore 64 emulator because it had a BASIC intepreter. But they've lightened up a bit.

It's definitely allowed for JS.

This looks like code to me, even if it is wrapped in JSON:

> {{#each posts}}

> {{# if ('type' in this) && (type=='stories') }}

If you create a tool that just converts IB views to JSON you can demonstrate progress much faster and learn and experiment with what the requirements of the final editor are. It will be much easier to stand up and way less effort than maintaining your own editor codebase while the project is young. Your time is the most valuable thing you have so don't spend it creating a new editor which could be its own project in itself. You want to put it towards expanding missing functionality between JSON and native components. One day when you find success and if you really still need to limit the user you can move all the functions you made for converting Interface Builder views into your own custom editor.

I think first thing I would do is take a very complicated interface view from a native project and analyze the view hierarchy and report errors to the user like "Warning: Nested UITableViews are not supported in Jasonette", "UIButton delegate will be ignored", etc. Then once you create this sort of 'unit test' that the IB is well-formatted you can then go about exporting it to JSON.

There may be a world where you actually are able to use all of the functionality of IB and don't ever have to have your own editor.

I think a good exercise would be to find a popular mobile app and recreate all of the functionality with Jasonette, developing missing features where you need them. A demo showing you recreate Tinder or iMessage by bolting a few pieces of logic together in Jasonette would go a long way in maturing the functionality and demonstrating its viability.

Have you considered weaving Parse or Firebase into this?