Preprocessor Macros in Xcode with Swift - xcode

Question

I'm having trouble replicating in Swift the Preprocessor Macro functionality offered by ObjC. I have heard that Swift has no preprocessor, so I'm looking for another way to implement this.
My end goal is to build my project using the command line tools, passing in a custom variable and value, which will be preprocessed and inserted into the code at specific points, before the build takes place.
This is the solution for ObjC:
Use this command to run a test:
xcodebuild \
test \
-scheme TestUserDefinedVariablesObjC \
-destination 'platform=iOS Simulator,name=iPhone 6' \
MY_VAR=42
I use MY_VAR in code like this:
int a = MY_VAR;
(I add MY_VAR to Preprocessor Macros in my target's Build Settings like this: MY_VAR=$(MY_VAR))
As a last resort, I could add pre-action to the scheme's Run phase that substitutes the correct values using sed or something like that, but it's not a great solution.

Answer 1

Are you using different keyset/keyboard? If so check "
example:
Preprocessor Macros in my target's Build Settings
MY_VAR=\"42\"
check " character. Change it with this "

Answer 2

Instead of using SED in a build-phase script, you could use the clang preprocessor.
For example, put this in a file named macro-test.c
#if DEBUG
#define LOG(A) print(A)
#else
#define LOG(A)
#endif
import Foundation
func hello()
{
LOG("Hello, Swift macro!")
let theAnswer = MY_CONST
print("The answer = ", theAnswer)
}
Add a script build phase that runs the clang preprocessor:
#!/bin/sh
if [ $CONFIGURATION == "Debug" ] ;
then
DEBUG="1"
else
DEBUG="0"
fi
MY_CONST=42
clang -E -P -DMY_CONST=$MY_CONST -DOS=$OS -DDEBUG=$DEBUG "${SOURCE_ROOT}/macro-test.c" > "${SOURCE_ROOT}/macro-test.swift"
Add the generated swift file to the Xcode project.