There is everything stopping you. WKWebView runs in its own process and has very limited options for integrating native code.

The model I was thinking of was native code in the native app, injected polyfill that talks to the native code over a message bus. The native code can draw over the top of the web view and pass messages in. Is there anything in particular stopping that?

I believe the problem is the "message bus" is pretty slow, and has pretty limited throughput, especially for something like audio and video.

IIRC that is exactly what ericsson did, they made a iOS browser that allowed webrtc years before apple by adding functionality to webviews.

Yes there is because you can't implement your own browser engine on iOS. Browsers are just shells for the safari engine on iPhones.

I've heard mixed reports on this - the big issue is technical in that you can't implement your own JIT Javascript engine, because only JavaScriptCore (running out-of-process) can write executable pages.

The big issue is that the app store rules forbid it.

> 2.5.6 Apps that browse the web must use the appropriate WebKit framework and WebKit Javascript.

Where did you get the impression I was suggesting implementing your own browser engine?

The whole point of the discussion surrounds what is possible in web views, not implementing your own browser engine.