Add the current version and build number on your iOS app icon

stamp-icon.rb

#!/usr/bin/env ruby

# Requires ImageMagick: `brew install imagemagick`
# Requires version.sh from https://gist.github.com/osteslag/1089407
#
# Set RGM_STAMP_VERSION_ON_ICONS=1 in your build settings to enable/disable
# stamping on Debug/Relase configurations.
#
# Make base unstamped versions Icon.base.png, &c. in the source tree. The
# script will make stamped versions Icon.png, &c. It relies on Xcode to copy
# resources so that they get properly compressed, so make sure this script step
# runs before "Copy Bundle Resources."
#
# Thanks Evan Doll (@edog1203), Krzysztof Zabłocki (@merowing), Joachim Bondo
# (@ostelag)
# see also:
# http://www.merowing.info/2013/03/overlaying-application-version-on-top-of-your-icon/
# http://stuff.bondo.net/post/7769890357/using-build-and-version-numbers-and-the-art-of

class NoSourceFileError < ArgumentError; end
class Icon

  attr_accessor :src, :dst

  def src= path
    if File.exist? path
      @src = path
    else
      raise NoSourceFileError, "no icon file at #{path}"
    end
  end

  def stamp_icon_with str
    `convert -background '#0008' -fill white -gravity center \
     -size #{banner_dims} caption:"#{str}" "#{@src}" +swap     \
     -gravity south -composite "#{@dst}"`
  end

  def banner_dims
    banner_ht = (dims[:ht] * 0.3).floor
    "#{dims[:wd]}x#{banner_ht}" # imagemagick-style format string
  end

  def dims
    return @dims if @dims
    data = `identify -format "%w %h" "#{@src}"`.strip.split.map(&:to_i)
    @dims = {:wd => data[0], :ht => data[1]}
  end

end

if (__FILE__ == $0)

  require 'fileutils'

  version = `Scripts/version --terse`.strip

  # just working from a base version in the source tree. Imagemagick can't
  # handle the Xcode-compressed PNGs in the built products directory. So
  # just stamp it and rely on Xcode to copy bundle resources normally.

  path = ENV['RGM_PATH_TO_ICONS']
  if ! path
    STDERR.puts "Error: RGM_PATH_TO_ICONS isn't set"
    exit 1
  end

  %w{Icon Icon@2x Icon-72 Icon-72@2x}.each do |stem|
    begin
      i = Icon.new
      i.src = File.join path, "#{stem}.base.png"
      i.dst = File.join path, "#{stem}.png"
      if (ENV['RGM_STAMP_VERSION_ON_ICONS'] == '1')
        i.stamp_icon_with version
      else
        FileUtils.cp i.src, i.dst
      end
    rescue NoSourceFileError => msg
      STDERR.puts "Warning: #{msg}"
    end
  end

end