Swift 语言中的 #ifdef 替换 [英] #ifdef replacement in the Swift language

问题描述

在 C/C++/Objective C 中，您可以使用编译器预处理器定义宏.此外，您可以使用编译器预处理器包含/排除部分代码.

In C/C++/Objective C you can define a macro using compiler preprocessors. Moreover, you can include/exclude some parts of code using compiler preprocessors.

#ifdef DEBUG
    // Debug-only code
#endif

Swift 中是否有类似的解决方案?

Is there a similar solution in Swift?

推荐答案

是的，你可以做到.

在 Swift 中，您仍然可以使用#if/#else/#endif"预处理器宏(尽管受到更多限制)，如 Apple 文档.举个例子:

In Swift you can still use the "#if/#else/#endif" preprocessor macros (although more constrained), as per Apple docs. Here's an example:

#if DEBUG
    let a = 2
#else
    let a = 3
#endif

现在，您必须在别处设置DEBUG"符号.在Swift Compiler - Custom Flags"部分的Other Swift Flags"行中设置它.您可以使用 -D DEBUG 条目添加 DEBUG 符号.

Now, you must set the "DEBUG" symbol elsewhere, though. Set it in the "Swift Compiler - Custom Flags" section, "Other Swift Flags" line. You add the DEBUG symbol with the -D DEBUG entry.

像往常一样，您可以在调试或发布时设置不同的值.

As usual, you can set a different value when in Debug or when in Release.

我用真实的代码测试过它，它工作正常；不过在操场上似乎没有人认出它.

I tested it in real code and it works; it doesn't seem to be recognized in a playground though.

您可以阅读我的原始帖子 此处.

You can read my original post here.

重要说明: -DDEBUG=1 不起作用.只有 -D DEBUG 有效.似乎编译器忽略了具有特定值的标志.

IMPORTANT NOTE: -DDEBUG=1 doesn't work. Only -D DEBUG works. Seems compiler is ignoring a flag with a specific value.

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