dump-strings.rb

#!/usr/bin/ruby

require "json"

all_strings = [ ]

`find . -path "*en.lproj*/*.strings"`.each_line do |line|
    JSON.parse(`plutil -convert json -o - \"#{line.chop}\"`).each_value do |value|
        all_strings.push(value.strip)
    end
end

all_strings.uniq!