how to find unused images from Xcode

#!/bin/sh
PROJ=`find . -name '*.xib' -o -name '*.[mh]'`

for png in `find . -name '*.png'`
do
    name=`basename $png`
    if ! grep -q $name $PROJ; then
        echo "$png is not referenced"
    fi
done

Credit:
http://mfaizanshaikh.wordpress.com/2012/12/17/how-to-remove-unused-images-from-xcode-project/