xcconfig:用于调试/发布的不同预处理器宏

问题描述

我创建并应用了一个简单的 .xcconfig 文件，其中包含

I have created and applied a simple .xcconfig file containing

GCC_PREPROCESSOR_DEFINITIONS[config=Debug] = FOODEBUG
GCC_PREPROCESSOR_DEFINITIONS[config=Release] = FOORELEASE

和 main.cpp 包含

and main.cpp containing

#include <iostream>

// This warning IS shown
#if DEBUG
#warning DEBUG is set to 1
#endif

// This warning IS NOT shown
#ifdef FOODEBUG
#warning FOODEBUG is set
#endif

// This warning IS NOT shown
#ifdef FOORELEASE
#warning FOORELEASE is set
#endif

int main(int argc, const char * argv[])
{
    // insert code here...
    std::cout << "Hello, World!\n";
    return 0;
}

现在我想知道为什么在 main.cpp 中，既没有定义 FOODEBUG 也没有定义 FOORELEASE ??!

Now I'm wondering why in main.cpp, neither FOODEBUG nor FOORELEASE are defined ??!

正如预期的那样，构建设置显示了我的 .xcconfig 文件的两行(Any Architecture | Any SDK")，但实际上并未使用它们.

As expected, the build settings show the two lines of my .xcconfig file ("Any Architecture | Any SDK"), but they are not actually used.

我怎么能做到这一点?

推荐答案

如果你有一个预处理器宏，你需要给它一个值才能像你一样使用它，请看我的一个项目设置的屏幕截图示例:

If you have a preprocessor macro you need to give it a value to be able to use it as you do, see a screenshot of one of my project setups as a sample:

之所以可以访问 DEBUG 是因为 #if 和 #ifdef 之间的行为不同.#if 当宏存在时为真，#ifdef 为非零值.我建议始终分配值 1 以进行保存，因为我不确定以上是否适用于所有编译器版本.

The reason why you can access DEBUG is difference is the different behaviour between #if and #ifdef.#if will be true when the macro exists, #ifdef if it has a non zero value. I suggest to always assign the value one to be save, because I'm not sure the above is true for all compiler versions.

更新:
以前不知道，但似乎 config=Debug 不起作用.尽管宏在设置中可见，但它们不会继承.有效的是 2 个与此类似的 xcconfig 文件:

UPDATE:
Did not know that before, but it seems config=Debug does not work. Although the macros get visible in the settings, they do not inherit up.What does work is 2 xcconfig files similar to this:

Release.xcconfig:

Release.xcconfig:

GCC_PREPROCESSOR_DEFINITIONS = $(inherited) FOORELEASE=1

调试.xcconfig

Debug.xcconfig

#include "Release.xcconfig"
GCC_PREPROCESSOR_DEFINITIONS = $(inherited) FOODEBUG=1

另请参阅 James Moores 的回答:如何在 xcconfig 变量中附加值?

Please also see James Moores answer here: How to append values in xcconfig variables?

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