RubyMotion: Adding a block to Teacup's animate_to_style, for completion

UIView.rb

# RubyMotion: Adding a block to Teacup's animate_to_style, for completion. You can do something like this
#
#    popup.animate_to_style( duration: 0.9, left: 5) do |finished|
#      popup.animate_to_style( duration: 0.3, left: 105) do |finished|
#        popup.animate_to_style( duration: 0.5, top: 300) do |finished|
#          popup.hidden = true
#        end
#      end
#    end
#
class UIView
   def animate_to_style(opts = {}, &block)
      UIView.animateWithDuration(
        opts.delete(:duration) || 0.3,
        delay: opts.delete(:delay) || 0,
        options: (opts.delete(:options) || UIViewAnimationOptionCurveEaseInOut),
        animations: lambda { style(opts) },
        completion: block)
   self
  end
end