从Swift调用C ++-std :: vector< T> [英] Calling C++ from Swift - what is the equivalent of std::vector<T>

问题描述

我正在通过 SwiftArchitect的示例之后的桥接标头从Swift调用C ++函数. C ++函数的签名是这样的:

I'm calling a C++ function from Swift via a bridging header following SwiftArchitect's example. The signature for the C++ function is this:

long GrabberInitializeAndProcess(
    unsigned char* pbInPixels,  
    int inStride,
    unsigned char* pbOutPixels, 
    int outStride,
    int width, 
    int height,
    Point mqTopLeft, 
    Size mqSize,
    std::vector<PolylineElement> * pForegroundMarks, 
    std::vector<PolylineElement> * pBackgroundMarks,
    void* pGrabberState );

(N.B.Point，Size和PolylineElement是本地C ++结构.)我在std::vector<T>的Objective-C ++包装器中使用什么签名?

(N.B. Point, Size, and PolylineElement are local C++ structs.) What signature do I use in my Objective-C++ wrapper for std::vector<T>?

推荐答案

您正在使用矢量作为指针.当您需要在Swift中使用它时非常好.

You are using vector as pointer. It's very good when you need use it in Swift.

您可以改用void*:

long GrabberInitializeAndProcess(
    unsigned char* pbInPixels,  
    int inStride,
    unsigned char* pbOutPixels, 
    int outStride,
    int width, 
    int height,
    Point mqTopLeft, 
    Size mqSize,
    void * pForegroundMarks, 
    void * pBackgroundMarks,
    void* pGrabberState );

并在实现中执行类型转换.

And perform typecasting in implementation.

或者，如果您需要打字安全性，可以白色:

Or if you need type safety, you can white:

typedef struct _vectorOfPolylineElement *vectorOfPolylineElementPtr;

long GrabberInitializeAndProcess(
    unsigned char* pbInPixels,  
    int inStride,
    unsigned char* pbOutPixels, 
    int outStride,
    int width, 
    int height,
    Point mqTopLeft, 
    Size mqSize,
    vectorOfPolylineElementPtr pForegroundMarks, 
    vectorOfPolylineElementPtr pBackgroundMarks,
    void* pGrabberState );

在实施中:

typedef struct _vectorOfPolylineElement
{
    std::vector<PolylineElement> val;
} *vectorOfPolylineElementPtr;

如果您实际上不需要GrabberInitializeAndProcess中的向量，只需使用它即可使用内存:

And if you actually don't need vector in GrabberInitializeAndProcess, just it elements you can work with memory:

long GrabberInitializeAndProcess(
    unsigned char* pbInPixels,  
    int inStride,
    unsigned char* pbOutPixels, 
    int outStride,
    int width, 
    int height,
    Point mqTopLeft, 
    Size mqSize,
    PolylineElement * pForegroundMarks, 
    size_t foregroundMarksCount,
    PolylineElement * pBackgroundMarks,
    size_t backgroundMarksCount,
    void* pGrabberState );

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