iOS POST file to Sinatra

ios_post_sinatra.rb

require 'sinatra'
 
require 'fileutils'
require 'json'
 
post '/:filename' do
	content_type :json
 
	puts "Opening directory"
	dirname = File.expand_path("~/my_dir")
	unless File.directory?(dirname)
		puts "Creating directory"
		FileUtils.mkdir_p(dirname)
	end
 
  filename = File.join(dirname, params[:filename])
  postedfile = params[:file] # The 'file' paramter is passed in with the request
 
	puts "Opening new file"
	File.open(filename, 'wb') do |file|
		puts "Writing file to disk"
		file.write(postedfile[:tempfile].read)
	end
 
	{ :success => 'true', :file => "#{filename}" }.to_json
end