Using existing Xcode projects via `prepare_command`

ReactiveCocoa.podspec

Pod::Spec.new do |s|
  s.name         = "ReactiveCocoa"
  s.version      = "3.0.0-alpha.1"
  s.summary      = "A framework for composing and transforming streams of values."
  s.description  = "ReactiveCocoa (RAC) is an Objective-C framework for Functional Reactive Programming. It provides APIs for composing and transforming streams of values."
  s.homepage     = "https://github.com/ReactiveCocoa/ReactiveCocoa/"
  s.license      = "MIT"
  s.author       = { "Josh Abernathy" => "josh@github.com" }
  #s.ios.deployment_target = "8.0"
  s.osx.deployment_target = "10.10"
  s.source       = { :git => "https://github.com/ashfurrow/ReactiveCocoa.git", :tag => s.version }

  s.prepare_command = <<-CMD
    xcodebuild -workspace ReactiveCocoa.xcworkspace -configuration Release -scheme 'ReactiveCocoa Mac'

    BUILT_PRODUCTS_DIR=`xcodebuild -workspace ReactiveCocoa.xcworkspace -configuration Release -scheme 'ReactiveCocoa Mac' -showBuildSettings|grep BUILT_PRODUCTS_DIR|head -n 1|awk '{ print $3 }'`
    
    rm -rf ReactiveCocoa.framework
    cp -a "$BUILT_PRODUCTS_DIR/ReactiveCocoa.framework" .
  CMD

  s.osx.preserve_paths       = 'ReactiveCocoa.framework'
  s.osx.public_header_files  = 'ReactiveCocoa.framework/Versions/A/Headers/*.h'
  s.osx.vendored_frameworks  = 'ReactiveCocoa.framework'
  s.osx.frameworks = ["Foundation", "AppKit"]
end