PromotionらしくUIImagePickerControllerを使う方法 ref: http://qiita.com/seisuke@github/items/627f052817c8072229bc

image_picker_screen.rb

class ImagePickerScreen < UIImagePickerController
  include ProMotion::ScreenModule

  def init
    if super
      self.delegate = self
    end
    self
  end

  def imagePickerController(picker, didFinishPickingMediaWithInfo:info)
    close value: :ok, picker: picker, info: info
  end

  def imagePickerControllerDidCancel(picker)
    close value: :cancel, picker: picker
  end

end