External objects passed to Lua end up being null when returned to ObjC

[tempelmann]

I have a script that declares a function that takes one object as a parameter and stores it in its global context. Another function returns that object.

When I use JavaScriptCore to pass JSExport objects via callWithArguments: to such a JavaScript program, then the returned object is still the same that was passed in.

However, trying the same with ObjC-Lua, the returned object is nil, even though the Lua code can still access the object's properties (meaning that the object still exists fine in Lua's context).

[tempelmann]

The reason for this is that toObjC() finds a value of type LUA_TUSERDATA on the stack, which it does not process.

[tempelmann]

Adding this to the switch cases in toObjC seems to resolve this.

case LUA_TUSERDATA:
{
	LuaWrapperObject *wrapper = (LuaWrapperObject*)lua_touserdata(L, index);
	return (__bridge id)wrapper->instance;
}

Not sure if this is always safe, i.e. that there are no other userdata types that could lead to misinterpretation.