Quick workaround for per-target asset catalog compilation using a Podfile post_install hook

Podfile

# ...

# Workaround for https://github.com/CocoaPods/CocoaPods/issues/1546
post_install do |installer|
  installer.aggregate_targets.each do |at|
    files = at.user_targets.map{|t|
      t.resources_build_phase.files_references.select{|f|
        f.last_known_file_type == 'folder.assetcatalog'
      }.map{|f|
        Pathname.new(f.real_path).relative_path_from(f.project.path.dirname)
      }
    }.flatten
    script = at.copy_resources_script_path
    files = files.join('" "')
    `sed -i '' 's@OTHER_XCASSETS=.*@XCASSET_FILES+=(\"#{files}\")@' '#{script}'`
  end
end