Find unreferenced png files in an Xcode workspace - xcode

Question

I have an Xcode workspace with several hundred png files and would like to list those which are unreferenced.
Example pngs:
capture-bg-1.png
capture-bg-1#2x.png
promo_icon.png
promo_icon#2x.png
Reference example for "promo_icon" (XML file):
<string>promo_icon</string>
Reference example for "promo_icon" (Objective-C):
[UIImage imageNamed:#"promo_icon"]
I want to get a list of filenames including "capture-bg-1" (presuming it has no matches like "promo_icon" does).
A little wrinkle is that there is a .pbxproj file (XML) that has a reference to every png file in the workspace so that file needs to be excluded from the search.
The following command gets all the unique filename parts (excluding folder and everything after '#' and '.') for evaluation.
find . -name *.png -exec basename {} \;| sed 's/[.#].*$//' | uniq
The grep part into which I would pipe the filename parts is the problem. This grep finds the files that do or do not reference 'promo_icon' and lists the references. An empty return value (no references) would be a png file I'm looking for a list of:
grep -I -R promo_icon . | grep -v pbxproj
However I can't figure out how to combine the two in a functional way. There is this snippet (https://stackoverflow.com/a/16258198/26235) for doing this in sh but it doesn't work.

Answer 1

An easier way to do this might be to put the list of all PNG names into one file, one per line. Then put the list of all references to PNG names into another file, one per line. Then grep -v -f the first file against the second. Whatever is returned is your answer.
First,
find . -name '*.png' -printf %f | sed -e 's/[.#].*$//' | sort -u > pngList
Then,
grep -RI --exclude .pbxproj -e '<string>.*png</string>' \
-e 'UIImage imageNamed' . > pngRefs
Finally,
grep -v -f pngList pngRefs
And you can clean up the results with sed and sort -u from there.
::edit::
The above approach could produce some wrong answers if you have any PNGs whose names are proper substrings of other PNGs. For example, if you have promo_icon and cheese_promo_icon and promo_icon is never referenced but cheese_promo_icon is referenced, the above approach will not detect that promo_icon is unreferenced.
To deal with this problem, you can surround your PNG name patterns with \b (word-boundary) sequences:
find . -name '*.png' -printf %f | sed -e 's/^/\\b/' -e 's/$/\\b/' -e 's/[.#].*$//' | sort -u > pngList
This way your pngList file will contain lines like this:
\bpromo_icon\b
\bcapture-bg-1\b
so when you grep it against the list of references it will only match when the name of each PNG is the entire name in the image ref (and not a substring of a longer name).

Answer 2

This is the script that finds unreferenced images in an Xcode project. One gotcha is that people may use string formatting to construct references to images and that's unaccounted for here. Mac users will want to install findutils via brew to get a version of find with printf:
#!/bin/sh
# Finds unreferenced PNG assets in an xcode project
# Get a list of png file stems, stripping out folder information, 'png' extension
# and '#2x' parts of the filename
for png in `find . -name '*.png' -printf '%f\n' | sed -e 's/[.#].*$//' | sort -u`
# Loop through the files and print out a list of files not referenced. Keep in mind
# that some files like 'asset-1' may be referred to in code like 'asset-%d' so be careful
do
name=`basename $png`
if ! grep -qRI --exclude project.pbxproj --exclude-dir Podfile $png . ; then
echo "$png is not referenced"
fi
done