RubyMotionでネットワークに置いたJSONを入力パラメタに使用 (webrick.rbはhttps://gist.github.com/Watson1978/4573005より) BubbleWrapが必要

param.json

{
	"brightness": 0.07,
	"saturation": 1.1,
	"sharpness": 0.1
}

view_controller.rb

BW::HTTP.get("http://localhost:8080/param.json") do |res|
  param = BW::JSON.parse(res.body.to_str)

  filter.brightness(param["brightness"])
  filter.saturation(param["saturation"])
  filter.sharpness(param["sharpness"])
end

webrick.rb

#!/usr/bin/env ruby
# -*- coding: utf-8 -*-
require "webrick"

DOC_ROOT    = "."
SERVER_PORT = 8080

s = WEBrick::HTTPServer.new(
  :Port => SERVER_PORT,
  :DocumentRoot => File.join(Dir::pwd, DOC_ROOT)
)
trap("INT") { s.shutdown }

s.start