Pre-action takes place before the build, so output doesn’t go to the build log, it goes to stdErr. You can copy the output to a file:
exec > ${PROJECT_DIR}/prebuild.log 2>&1
echo "hello world"
To get the environment variables to work, you also need to set “Provide build settings from” to the appropriate target.
That should write hello world to a file named “prebuild.log” in your project folder.
for XCode versions < 13.2
If you want these activities to end up in the build log, consider adding a run script to your target’s build phase instead.
for XCode versions >= 13.2
The XCode build log now includes a Run pre-actions section. If you don’t redirect to a file, those messages will end up as the last item in a ‘Run custom shell script’ in this section – access via the XCode Report Navigator.
