问题
I have a configuration that I'd like to dynamically control a preprocessor defined value through an environment variable.
Is this possible? if it is how do I set in the preprocessor define table that I want to set the value based on the environment variable?
回答1:
In the "Build Settings" of a target of your project, you can add something like that to the "Preprocessor Macros" field:
DEV_USERNAME="${USER}"
Of course, the USER variable can be replaced by any environment variable available to Xcode build system. To get a list of those, you can add a run script to your target and enable the checkmark "Show environment variables in build log."
You can then use the DEV_USERNAME preprocessor macro in your code. And if you want to use it as a string, you can "stringify" it:
#define xstr(s) str(s)
#define str(s) #s
xstr(DEV_USERNAME)
This will give you the username surrounded by double quotes.
来源：https://stackoverflow.com/questions/9088380/xcode-preprocessor-dependent-on-environment-variable