斯威夫特是否不函数指针工作？ [英] Does Swift not work with function pointers?

问题描述

我想斯威夫特使用C库，和我有麻烦调用，它接受一个函数指针作为它的一个参数的函数。例如，我想在斯威夫特利用lua.h文件的一部分是这样的：

I'm trying to use a C library in Swift, and I'm having trouble calling any function that takes a function pointer as one of it's arguments. For example, part of the lua.h file that I'm trying to use in Swift looks like this:

LUA_API void  (lua_setuservalue) (lua_State *L, int idx);


typedef int (*lua_CFunction) (lua_State *L);

LUA_API void  (lua_callk) (lua_State *L, int nargs, int nresults, int ctx,
                       lua_CFunction k);

我用桥接报头以获得进入图书馆，并从我的雨燕code我可以叫 lua_setuservalue 没有任何麻烦。但是，如果我尝试调用的 lua_callk 我得到使用未解决的标识符lua_callk'的。如果我从声明中删除函数指针的 lua_callk 后，我不再出现此错误。任何帮助是相当AP preciated。

I use the bridging header to get access to the library, and from my Swift code I can call lua_setuservalue without any trouble. But if I try to call lua_callk I get "use of unresolved identifier 'lua_callk'". If I remove the function pointer from the declaration for lua_callk, I no longer get this error. Any help is quite appreciated.

推荐答案

苹果已经可以作为测试3的函数指针，但它们只能被引用不叫。

Apple has made function pointers available as of beta 3, however they can only be referenced not called.

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C函数指针被导入到斯威夫特 CFunctionPointer＆LT;类型＆GT; ，其中键入是一个
  斯威夫特函数类型。例如，具有类型的函数指针 INT（*）（无效）用C
  导入斯威夫特 CFunctionPointer≤（） - GT; INT32＆GT;

Function Pointers

C function pointers are imported into Swift as CFunctionPointer<Type>, where Type is a Swift function type. For example, a function pointer that has the type int (*)(void) in C is imported into Swift as CFunctionPointer<() -> Int32>

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函数指针现在也进口，并且可以参考与周围通过。然而，
  你不能调用C函数指针或闭合转换为C函数指针类型。

Function pointers are also imported now, and can be referenced and passed around. However, you cannot call a C function pointer or convert a closure to C function pointer type.

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