Rake task to clean unused images in your iOS project

clean_assets.rb

desc 'Remove unused images'
task :clean_assets do
  require 'set'

  all = Set.new
  used = Set.new
  unused = Set.new

  # White list
  used.merge %w{Icon Icon-29 Icon-50 Icon-58 Icon-72 Icon-114}

  regex = /\[UIImage imageNamed:@"([a-zA-Z0-9\-_]+).png"\]/
  Dir.glob('Classes/*.m').each do |path|
    used.merge File.open(path).read.scan(regex).flatten
  end

  Dir.glob('Resources/Images/*.png').each do |path|
    next if path.include? '@2x.png'
    all << path.gsub(/Resources\/Images\/([a-zA-Z0-9\-_]+).png/, "\\1")
  end

  unused = all - used
  unused.each do |key|
    `rm -f Resources/Images/#{key}.png Resources/Images/#{key}@2x.png`
  end

  puts "#{all.length} total found"
  puts "#{used.length} used found"
  puts "#{unused.length} deleted"
end