Increment Xcode project build number

IncrementBuildNumber.rb

#!/usr/bin/ruby

# Call via a run script build phase:
#
#    ${SRCROOT}/IncrementBuildNumber.rb
#

require 'fileutils'
require 'pathname'

project_path = Pathname.new(ENV['SOURCE_ROOT'])
project_name = ENV['PROJECT_NAME']
plist_file = project_path + project_name + "#{project_name}-Info.plist"

unless File.exists?(plist_file)
  puts "cannot find project info.plist file at path: #{plist_file}"
  exit 1
end

v = `/usr/libexec/PlistBuddy -c "Print CFBundleVersion" "#{plist_file}" 2>/dev/null`
v.strip!
if v.empty?
  puts "\"#{plist_file}\" does not contain key: \"CFBunleVersion\""
  exit 2
end

v_parts = v.split('.')
unless v_parts.count == 4
  puts "\"#{v}\" is not in expected format: 0.0.0.0"
  exit 3
end

major = v_parts[0]
minor = v_parts[1]
revision = v_parts[2]
build = Integer("#{v_parts[3]}")

build += 1

`/usr/libexec/PlistBuddy -c \"Set :CFBundleVersion #{major}.#{minor}.#{revision}.#{build.to_s}\" \"#{plist_file}\"`