step_count_extractor.rb

#!/usr/bin/ruby
# Parses the XML format that iOS' HealthKit export feature creates, extracting step counts and dumping out a CSV
require 'nokogiri'
require 'date'

filename = ARGV[0]

def process_date(date)
  DateTime.parse(date).strftime('%Y-%m-%d %H:%M:%S')
end

xml = Nokogiri::XML(File.open(filename))

puts %w( type source unit startDate endDate value recordCount).join(',')

xml.xpath("//Record[@type='HKQuantityTypeIdentifierStepCount']").each do |record|
   ret = [
           record['type'],
           record['source'],
           record['unit'],
           process_date(record['startDate']),
           process_date(record['endDate']),
           record['value'],
           record['recordCount']
   ]

   puts ret.join(',')
end