#ifdef replacement in the Swift language

Question

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.

Answer 1

A major change of ifdef replacement came up with Xcode 8. i.e use of Active Compilation Conditions.

Refer to Building and Linking in Xcode 8 Release note.

New build settings

New setting: SWIFT_ACTIVE_COMPILATION_CONDITIONS

“Active Compilation Conditions” is a new build setting for passing conditional compilation flags to the Swift compiler.

Previously, we had to declare your conditional compilation flags under OTHER_SWIFT_FLAGS, remembering to prepend “-D” to the setting. For example, to conditionally compile with a MYFLAG value:

#if MYFLAG1
    // stuff 1
#elseif MYFLAG2
    // stuff 2
#else
    // stuff 3
#endif

The value to add to the setting -DMYFLAG

Now we only need to pass the value MYFLAG to the new setting. Time to move all those conditional compilation values!

Please refer to below link for more Swift Build Settings feature in Xcode 8: http://www.miqu.me/blog/2016/07/31/xcode-8-new-build-settings-and-analyzer-improvements/