为C ++库创建一个Objective-C包装器 [英] Making a Objective-C Wrapper for a C++ Library

问题描述

我想在Objective-C中创建一个包装，所以我不必在库类之外编写c ++。

I am trying to make a wrapper in Objective-C so I don't have to write c++ outside the library classes.

库主文件是 LLAHProcessor.h .cpp

我的包装器是 LLAHProcessorWrapper.h .mm

它编译正常，但当我将 LLAHProcessorWrapper 添加到其他类一个成员变量我得到了几百个错误，如：

It compiles fine, but when I add LLAHProcessorWrapper to other class, (Lets say an UIView) as a member variable I get hundreds of errors, like:

#include <map> : Map no such a file or directory

b
$ b

and in every c++ class/struct:

Expected specifier-qualifier list before ClassName

就像编译器不能识别c ++代码。

Is like compiler is not recognizing c++ code.

我想知道我在这里缺少什么。
它是否必须是这样的事实，我添加到Xcode目标属性：？

I wonder what am I missing here. Does it has to be something with the fact I added this to Xcode Target Properties: ?

Other Link Flags : -lstdc++ -lz

或者我需要在这里添加新标志吗？

Or maybe I need to add new flags here?

提前感谢

推荐答案

您的问题是 .m 文件编译为C而不是C ++。因此，当编译一个 .m 文件时，编译器遇到任何C ++甚至在头文件中时，它都会barf。

Your problem is that .m files are compiled as C instead of C++. Thus when the compiler comes across any C++ even in a header file while compiling a .m file, it will barf.

毫无疑问，你必须在你的头文件中加入一些C ++，因为你的Objective C对象包装了一个C ++对象，但是有一些方法。一种方法是使用指向C ++对象的指针，并使用为C ++（和Objective-C ++）定义的方便的预处理器define __ cplusplus ，而不是C或Objective-C）例如

No doubt you have to put some C++ in your header file because your Objective C object wraps a C++ object, but there are ways around this. One way would be to use a pointer to the C++ object and make use of the handy preprocessor define __cplusplus which is defined for C++ (and Objective-C++) but not for C (or Objective-C) e.g.

// LLAHProcessorWrapper.h

#if defined __cplusplus
class MyCPPClass;    // forward class declaration
#else
typedef struct MyCPPClass MyCPPClass;   // forward struct declaration
#endif

@interface MyOCClass : NSObject
{
@private
    MyCPPClass* cppObject;
} 

// methods and properties

@end

因为你永远不会解除cppObject的成员在 .mm 文件之外，所以你不必为结构提供完整的定义。

Since you never dereference the members of the cppObject outside of the .mm file it doesn't matter that you never provide a full definition for the struct.

您将新和 delete -init 和 -dealloc 。您将在 LLAHProcessorWrapper.mm 中包含完整的C ++类声明。

You would new and delete the pointer in -init and -dealloc respectively. You would include the full C++ class declaration in LLAHProcessorWrapper.mm.

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