Small script to rename iOS app icons

rename_appicons.rb

require "fileutils"
require "json"

json = File.open("Contents.json", "r+")
contents = JSON.load(json.read)

contents["images"].map do |image|
  ext = File.extname(image["filename"])
  new_filename = "#{image["size"]}@#{image["scale"]}#{ext}"
  FileUtils.mv(image["filename"], new_filename)
  image["filename"].replace(new_filename)
end

json.rewind
json.write(JSON.pretty_generate(contents))
json.close