explore iOS support

[progrium]

This would require making sure our generation tooling is fully parameterized for platform (it mostly is now), and generating into an ios directory. Start with basic frameworks Foundation and UIKit. First make something that can run on the iPhone simulator. Then figure out how to deploy to actual device.

The original objc project we were originally based on had a demo for ios support, which would be a starting point for some of this:
https://github.com/mkrautz/objc/tree/master/demo-ios