"The JavaScriptCore Framework is still private on iOS. So as it is now, I won't be allowed to distribute the game in the AppStore. But my understanding is, that if I bundle my own copy of the JavaScriptCore Framework (which is part of WebKit and thus freely available) with my game, I should be on the safe side."
This is true. You can compile Javascript Core and include it in your app. I have done this previously as an experiment.
However, there is one HUGE drawback in doing so: no compiled/jitted javascript code is possible.
This is because iOS applications are not allowed to create executable code in the heap or on the stack, so there is no way for JavaScriptCore to compile to native code when it is running as part of a third party application.
So unfortunately there is no good way to get this going at the same speed that you get when linking against the private framework.
Sad. This is also a major problem for other scripting languages. They all can only run in interpreted mode. Which might be good enough but is never the best you can get.
Yep, I hit this roadblock too. For my similar project I ended up using a non-jit version of Spidermonkey for embedded Javascript. Interpreted performance is pretty poor in comparison to jit though, and I ended up moving to a much higher level Javascript API to share between canvas and native implementations. It runs at 60 fps on 2nd gen hardware now with moderate (1 - 2 hundred sprites).
I wonder how feasible it would be to pre-compile the Javascript to machine code before distributing it? Maybe someone determined enough could probably hack one of the existing JIT engines to emit executable machine code to a file?
For a restricted subset of Javascript it wouldn't be that hard.
I'm not sure that solves the iphone problem though - I don't think it's kosher to use non c/c++/objc code. A Javascript to C compiler would work fine, though. That would be quite a bit more work, though.
[Edit]As pointed out below, it might well be ok. I guess you'd have to somehow get the generated machine code into a static library and link it with your application. That might work.
This is true. You can compile Javascript Core and include it in your app. I have done this previously as an experiment.
However, there is one HUGE drawback in doing so: no compiled/jitted javascript code is possible.
This is because iOS applications are not allowed to create executable code in the heap or on the stack, so there is no way for JavaScriptCore to compile to native code when it is running as part of a third party application.
So unfortunately there is no good way to get this going at the same speed that you get when linking against the private framework.
Sad. This is also a major problem for other scripting languages. They all can only run in interpreted mode. Which might be good enough but is never the best you can get.