在 Xcode 中使用 MACOSX_DEPLOYMENT_TARGET 对 Cocoa 应用程序进行条件编译
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Conditional compilation using MACOSX_DEPLOYMENT_TARGET in Xcode for a Cocoa app
提问by user532477
In a Cocoa application, I'd like to use conditional compilation, like:
在 Cocoa 应用程序中，我想使用条件编译，例如：
#if MACOSX_DEPLOYMENT_TARGET <= MAC_OS_X_VERSION_10_4
[[NSFileManager defaultManager] removeFileAtPath:path handler:nil];
#else
[[NSFileManager defaultManager] removeItemAtPath:path error:NULL];
#endif
My hope is that this will avoid compiler warnings about removeFileAtPath: being deprecated when MACOSX_DEPLOYMENT_TARGET = 10.6, since it shouldn't be compiling that line.
我希望这将避免编译器警告关于 removeFileAtPath: 在 MACOSX_DEPLOYMENT_TARGET = 10.6 时被弃用，因为它不应该编译该行。
It doesn't work.
它不起作用。
When MACOSX_DEPLOYMENT_TARGET = 10.6 I get a warning that removeFileAtPath: is deprecated. But it shouldn't be compiling that line, so it shouldn't be warning about it having a deprecated method!
当 MACOSX_DEPLOYMENT_TARGET = 10.6 时，我收到一条警告，提示 removeFileAtPath: 已弃用。但它不应该编译该行，因此不应该警告它有一个已弃用的方法！
(I am setting MACOSX_DEPLOYMENT_TARGET in both the project build settings and the target build settings. I have BASE_SDK set to 10.6 and specify GCC 4.2 in both, too.)
（我在项目构建设置和目标构建设置中都设置了 MACOSX_DEPLOYMENT_TARGET。我将 BASE_SDK 设置为 10.6 并在两者中指定 GCC 4.2。）
What am I doing wrong? Do I have some fundamental misunderstanding of conditional compilation?
我究竟做错了什么？我对条件编译有一些基本的误解吗？
回答by Laurent Etiemble
MACOSX_DEPLOYMENT_TARGETis mostly used to perform a weak-linking. You should use MAC_OS_X_VERSION_MIN_REQUIREDinstead to perform conditional compilation:
MACOSX_DEPLOYMENT_TARGET主要用于执行弱链接。您应该使用MAC_OS_X_VERSION_MIN_REQUIRED代替来执行条件编译：
#if MAC_OS_X_VERSION_MIN_REQUIRED < MAC_OS_X_VERSION_10_5
[[NSFileManager defaultManager] removeFileAtPath:path handler:nil];
#else
[[NSFileManager defaultManager] removeItemAtPath:path error:NULL];
#endif
See Ensuring Backwards Binary Compatibility - Weak Linking and Availability Macros on Mac OS Xfrom Apple for more examples.
有关更多示例，请参阅确保向后二进制兼容性 - Mac OS X 上的弱链接和可用性宏。
