POC of a Pod which installs a run script into Xcode (CocoaPods 0.33 or less)

install_run_script.rb

#!/usr/bin/env ruby

require 'pathname'
require 'xcodeproj'

path_to_xcode_build_script = '"${SRCROOT}/Pods/POD_NAME/run_script.sh"'
xcode_build_script_name = 'Unique Run Script Name'

puts Dir.pwd
puts ARGV[0]

path_to_spec = ARGV[0] # Passed from podspec using path variable

if path_to_spec.start_with?('/private/tmp/CocoaPods/Lint')
  # CocoaPods Lint
  # e.g. /private/tmp/CocoaPods/Lint/Pods/Local Podspecs/POD_NAME.podspec

  puts 'CocoaPods linting, bail now before fail'
  exit 0
elsif path_to_spec.include?('.cocoapods')
  # Pod installed from spec repo
  # podspec: /Users/ben/.cocoapods/repos/REPO_NAME/POD_NAME/1.0.0/POD_NAME.podspec
  # Dir.pwd: /Users/ben/APP_PATH/Pods/POD_NAME

  path_to_project = Dir.glob(Pathname.new(Dir.pwd) + '../../*.xcodeproj')[0]
else
  # Pod installed via :path in Podfile
  # podspec: /Users/ben/LOCAL_POD_PATH/POD_NAME/POD_NAME.podspec
  # Dir.pwd: /Users/ben/LOCAL_POD_PATH/POD_NAME

  path_to_project = Dir.glob(Pathname.new(path_to_spec) + '../../../*.xcodeproj')[0]
end

puts path_to_project

project = Xcodeproj::Project.open(path_to_project)
main_target = project.targets.first
script_installed = false

main_target.shell_script_build_phases.each { |run_script|
  script_installed = true if run_script.name == xcode_build_script_name
}

if (!script_installed)
  puts "Installing run script in Xcode project #{path_to_project}"
  phase = main_target.new_shell_script_build_phase(xcode_build_script_name)
  phase.shell_script = path_to_xcode_build_script
  project.save()
else
  puts "Run script already installed"
end

POD_NAME.podspec

Pod::Spec.new do |s|
  s.name     = 'POD_NAME'
  s.version  = '1.0.0'
  s.license  = { :type => 'MIT', :file => 'LICENSE' }
  s.summary  = 'Example of pod which installs a run script into the Xcode project (first target)'
  s.homepage = 'https://github.com/phatblat/POD_NAME'
  s.authors  = { 'Ben Chatelain' => '[email protected]' }
  s.source   = { :git => 'https://github.com/phatblat/POD_NAME.git', :tag => s.version.to_s }

  s.ios.deployment_target = '6.0'
  s.requires_arc    = true
  s.source_files    = "Classes/**/*.{h,m}"
  s.preserve_paths  = 'run_script.sh', 'install_run_script.rb'

  s.prepare_command = "ruby install_run_script.rb '#{path}'"
end

run_script.sh

#!/bin/sh

echo "Every build is awesome!"

This gist is obsolete now.

@umangbistra2, as @castellet88 noted the script_phase attribute is the right way to create these run scripts today. You can even have CocoaPods install a ruby script using :shell_path => '/usr/bin/ruby'.