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

User · Answer

For Xcode 9 4 1 and C   project  Adding const char  Preprocessor Macros to both Debug and Release builds    Select your project   Select Build Settings   Search  Preprocessor Macros     Open interactive list   Add your macros and don t forget to escape quotation   Use in source code as common const char        ifndef JSON DEFINITIONS FILE PATH static constexpr auto JSON DEFINITIONS FILE PATH    definitions json    endif     FILE  pFileIn   fopen JSON DEFINITIONS FILE PATH   r

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

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

User · Answer

You don t need to create a user-defined setting   The built-in setting  Preprocessor Macros  works just fine  alt text http   idisk mac com cdespinosa Public Picture 204 png  If you have multiple targets or projects that use the same prefix file  use Preprocessor Macros Not Used In Precompiled Headers instead  so differences in your macro definition don t trigger an unnecessary extra set of precompiled headers

User · Answer

You don t need to create a user-defined setting   The built-in setting  Preprocessor Macros  works just fine  alt text http   idisk mac com cdespinosa Public Picture 204 png  If you have multiple targets or projects that use the same prefix file  use Preprocessor Macros Not Used In Precompiled Headers instead  so differences in your macro definition don t trigger an unnecessary extra set of precompiled headers

User · Answer

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

User · Answer

For Xcode 9 4 1 and C   project  Adding const char  Preprocessor Macros to both Debug and Release builds    Select your project   Select Build Settings   Search  Preprocessor Macros     Open interactive list   Add your macros and don t forget to escape quotation   Use in source code as common const char        ifndef JSON DEFINITIONS FILE PATH static constexpr auto JSON DEFINITIONS FILE PATH    definitions json    endif     FILE  pFileIn   fopen JSON DEFINITIONS FILE PATH   r

User · Answer

As an addendum  if you are using this technique to define strings in your target  this is how I had to define and use them   In Build Settings -  Preprocessor Macros  and yes backslashes are critical in the definition   APPURL NSString     www foobar org     And in the source code   objectManager client baseURL   APPURL NSString

User · Answer

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

User · Answer

You don t need to create a user-defined setting   The built-in setting  Preprocessor Macros  works just fine  alt text http   idisk mac com cdespinosa Public Picture 204 png  If you have multiple targets or projects that use the same prefix file  use Preprocessor Macros Not Used In Precompiled Headers instead  so differences in your macro definition don t trigger an unnecessary extra set of precompiled headers

User · Answer

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

User · Answer

You can use the   Prefix pch file to declare project wide macros  That file is usually in you Other Sources group

User · Answer

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

User · Answer

As an addendum  if you are using this technique to define strings in your target  this is how I had to define and use them   In Build Settings -  Preprocessor Macros  and yes backslashes are critical in the definition   APPURL NSString     www foobar org     And in the source code   objectManager client baseURL   APPURL NSString

User · Answer

You can use the   Prefix pch file to declare project wide macros  That file is usually in you Other Sources group

User · Answer

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

User · Answer

You don t need to create a user-defined setting   The built-in setting  Preprocessor Macros  works just fine  alt text http   idisk mac com cdespinosa Public Picture 204 png  If you have multiple targets or projects that use the same prefix file  use Preprocessor Macros Not Used In Precompiled Headers instead  so differences in your macro definition don t trigger an unnecessary extra set of precompiled headers

[objective-c] How to define a preprocessor symbol in Xcode

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