If you want something like this

You can add custom bush script before or after building, running, testing, archiving and so on!
Steps:
1. Navigate to your project's build phases in Xcode, click on the + sign towards the top left of the window, and then click on "New Run Script Build Phase" in the drop down menu:

2.
You should then see a new section added where you can inject your bash script.
In the body of your run script build phase, copy and paste this lovely bit of code:
TAGS="TODO:|FIXME:"
find "${SRCROOT}" \( -name "*.h" -or -name "*.m" -or -name "*.swift" \) -print0 | xargs -0 egrep --with-filename --line-number --only-matching "($TAGS).*\$" | perl -p -e "s/($TAGS)/ warning: \$1/"
3.
From here on out, you should now see warnings when you mark your code with TODO: or FIXME: comment blocks! Here's a screenshot:

For more details see this article by krakendev.io