How to define a preprocessor symbol in Xcode

Question

Is it possible to set a symbol for conditional compilation by setting up properties in an Xcode project?

My aim is to to create a symbol that is available to all files, without having to use import/include, so that a set of common classes can have a special behavior in some projects. Like the following, but with my own symbols.

#if TARGET_IPHONE_SIMULATOR
    ...
#endif

Answer 1

Go to your Target or Project settings, click the Gear icon at the bottom left, and select "Add User-Defined Setting". The new setting name should be GCC_PREPROCESSOR_DEFINITIONS, and you can type your definitions in the right-hand field.

Per Steph's comments, the full syntax is:

 constant_1=VALUE constant_2=VALUE

Note that you don't need the '='s if you just want to #define a symbol, rather than giving it a value (for #ifdef statements)

Answer 2

It's under "GCC 4.2 Preprocessing" (or just put "prepro" in the search box)...

...however, for the life of me I can't get it to work.

I have my standard Debug and Release configurations, and I want to define DEBUG=1 in the debugging configuration. But after adding it as a value:

(in the settings window) > Preprocessor Macros : DEBUG=1

#if DEBUG
    printf("DEBUG is set!");
#endif

...never prints/gets called. It's driving me crazy...

Answer 3

Instead of #if DEBUG, try

#if defined(DEBUG)

or

#ifdef DEBUG

Answer 4

In response to Kevin Laity's comment (see cdespinosa's answer), about the GCC Preprocessing section not showing in your build settings, make the Active SDK the one that says (Base SDK) after it and this section will appear. You can do this by choosing the menu Project > Set Active Target > XXX (Base SDK). In different versions of XCode (Base SDK) maybe different, like (Project Setting or Project Default).

After you get this section appears, you can add your definitions to Processor Macros rather than creating a user-defined setting.

Answer 5

Question: I find the GCC 4.2 Preprocessing section only in the Release configuration, not in the Debug configuration for my project. I want to use

ifdef DEBUG_MODE

to conditionalize code that writes stuff to the console. Should there be such a section in the Debug configuration? If not, can I add one?

Thx

Steve

Answer 6

You can duplicate the target which has the preprocessing section, rename it to any name you want, and then change your Preprocessor macro value.