从C ++调用Swift函数 [英] Calling a Swift function from C++

问题描述

我想知道是否可以从C ++调用Swift函数?如果是的话，怎么办?我知道我们可以从Swift调用C ++函数，但是我还没有找到确切的答案.

I was wondering if it's possible to call a Swift function from C++? And if YES, how? I know that we can call a C++ function from Swift but I haven't found an exact answer about this.

推荐答案

虽然没有正式的方法可以直接从C调用Swift函数，但是您可以设置一个可以从C调用的函数指针.是否可以帮助您取决于您​​的确切情况.例如，在Apple平台上，与使用C回调(例如CFRunLoop观察器)的C API集成非常有用.

While there’s no official way to call a Swift function directly from C, you can set up a function pointer that’s callable from C. Whether that helps you depends on your exact circumstances. For example, on Apple platforms it’s super useful for integrating with C APIs that use C callbacks (things like CFRunLoop observers).

以下示例中粘贴了一个没有Apple风格的示例.

Pasted in a below is an example sans anything Apple-ish.

分享并享受-奎因爱斯基摩人！"Apple开发人员关系，开发人员技术支持，核心操作系统/硬件让myEmail ="eskimo"+"1"+"@ apple.com"

Share and Enjoy — Quinn "The Eskimo!" Apple Developer Relations, Developer Technical Support, Core OS/Hardware let myEmail = "eskimo" + "1" + "@apple.com"

// main.swift

private func printGreeting(modifier: UnsafePointer<CChar>) {
    print("Hello \(String(cString: modifier))World!")
}

var callbacks = SomeCLibCallbacks(
    printGreeting: { (modifier) in
        printGreeting(modifier: modifier)
    }
)
SomeCLibSetup(&callbacks)

SomeCLibTest()

// SomeCLib.h

#ifndef SomeCLib_h
#define SomeCLib_h

struct SomeCLibCallbacks {
    void (* _Nonnull printGreeting)(const char * _Nonnull modifier);
};
typedef struct SomeCLibCallbacks SomeCLibCallbacks;

extern void SomeCLibSetup(const SomeCLibCallbacks * _Nonnull callbacks);

extern void SomeCLibTest(void);

#endif

// SomeCLib.c

#include "SomeCLib.h"

static SomeCLibCallbacks sCallbacks;

extern void SomeCLibSetup(const SomeCLibCallbacks * callbacks) {
    sCallbacks = *callbacks;
}

extern void SomeCLibTest(void) {
    sCallbacks.printGreeting("Cruel ");
}

来源: https://forums.swift.org/t/best-way-to-call-a-swift-function-from-c/9829/2

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