A script to generate .strings file for .swift, .m, .storyboard and .xib files by genstrings and ibtool commands, and merge them with existing translations.

mergegenstrings.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-
 
# Localize.py - Incremental localization on XCode projects
# João Moreno 2009
# http://joaomoreno.com/
 
# Modified by Steve Streeting 2010 http://www.stevestreeting.com
# Changes
# - Use .strings files encoded as UTF-8
#   This is useful because Mercurial and Git treat UTF-16 as binary and can't 
#   diff/merge them. For use on iPhone you can run an iconv script during build to 
#   convert back to UTF-16 (Mac OS X will happily use UTF-8 .strings files).
# - Clean up .old and .new files once we're done

# Modified by Yoichi Tagaya 2015 http://github.com/yoichitgy
# Changes
# - Use command line arguments to execute as `mergegenstrings.py path routine`
#     path: Path to the directory containing source files and lproj directories.
#     routine: Routine argument for genstrings command specified with '-s' option.
# - Support both .swift and .m files.
# - Support .storyboard and .xib files.
 
from sys import argv
from codecs import open
from re import compile
from copy import copy
import os
 
re_translation = compile(r'^"(.+)" = "(.+)";$')
re_comment_single = compile(r'^/\*.*\*/$')
re_comment_start = compile(r'^/\*.*$')
re_comment_end = compile(r'^.*\*/$')
 
class LocalizedString():
    def __init__(self, comments, translation):
        self.comments, self.translation = comments, translation
        self.key, self.value = re_translation.match(self.translation).groups()
 
    def __unicode__(self):
        return u'%s%s\n' % (u''.join(self.comments), self.translation)
 
class LocalizedFile():
    def __init__(self, fname=None, auto_read=False):
        self.fname = fname
        self.strings = []
        self.strings_d = {}
 
        if auto_read:
            self.read_from_file(fname)
 
    def read_from_file(self, fname=None):
        fname = self.fname if fname == None else fname
        try:
            f = open(fname, encoding='utf_8', mode='r')
        except:
            print 'File %s does not exist.' % fname
            exit(-1)
         
        line = f.readline()
        while line:
            comments = [line]
 
            if not re_comment_single.match(line):
                while line and not re_comment_end.match(line):
                    line = f.readline()
                    comments.append(line)
             
            line = f.readline()
            if line and re_translation.match(line):
                translation = line
            else:
                raise Exception('invalid file')
             
            line = f.readline()
            while line and line == u'\n':
                line = f.readline()
 
            string = LocalizedString(comments, translation)
            self.strings.append(string)
            self.strings_d[string.key] = string
 
        f.close()
 
    def save_to_file(self, fname=None):
        fname = self.fname if fname == None else fname
        try:
            f = open(fname, encoding='utf_8', mode='w')
        except:
            print 'Couldn\'t open file %s.' % fname
            exit(-1)
 
        for string in self.strings:
            f.write(string.__unicode__())
 
        f.close()
 
    def merge_with(self, new):
        merged = LocalizedFile()
 
        for string in new.strings:
            if self.strings_d.has_key(string.key):
                new_string = copy(self.strings_d[string.key])
                new_string.comments = string.comments
                string = new_string
 
            merged.strings.append(string)
            merged.strings_d[string.key] = string
 
        return merged
 
def merge(merged_fname, old_fname, new_fname):
    try:
        old = LocalizedFile(old_fname, auto_read=True)
        new = LocalizedFile(new_fname, auto_read=True)
        merged = old.merge_with(new)
        merged.save_to_file(merged_fname)
    except:
        print 'Error: input files have invalid format.'
 
 
STRINGS_FILE = 'Localizable.strings'
 
def localizeCode(path, routine):
    print 'Localize source code...'
    languages = [lang for lang in [os.path.join(path, name) for name in os.listdir(path)]
                if lang.endswith('.lproj') and os.path.isdir(lang)]
    for language in languages:
    	print language
        original = merged = os.path.join(language, STRINGS_FILE)
        old = original + '.old'
        new = original + '.new'
     
        if os.path.isfile(original):
            os.rename(original, old)
            os.system('genstrings -q -s %s -o "%s" `find %s -name "*.swift" -o -name "*.m"`' % (routine, language, path))
            os.system('iconv -f UTF-16 -t UTF-8 "%s" > "%s"' % (original, new))
            merge(merged, old, new)
        else:
            os.system('genstrings -q -s %s -o "%s" `find %s -name "*.swift" -o -name "*.m"`' % (routine, language, path))
            os.rename(original, old)
            os.system('iconv -f UTF-16 -t UTF-8 "%s" > "%s"' % (old, original))
         
        if os.path.isfile(old):
            os.remove(old)
        if os.path.isfile(new):
            os.remove(new)
 
def localizeInterface(path, developmentLanguage):
    baseDir = os.path.join(path, "Base.lproj")
    developmentLanguage = os.path.splitext(developmentLanguage)[0] + ".lproj" # Add the extension if not exists
    print developmentLanguage
    if os.path.isdir(baseDir):
        print 'Localize interface...'
        ibFileNames = [name for name in os.listdir(baseDir) if name.endswith('.storyboard') or name.endswith('.xib')]
        languages = [lang for lang in [os.path.join(path, name) for name in os.listdir(path)]
                    if lang.endswith('.lproj') and not lang.endswith('Base.lproj') and os.path.isdir(lang)]
        for language in languages:
            print language
            for ibFileName in ibFileNames:
                ibFilePath = os.path.join(baseDir, ibFileName)
                stringsFileName = os.path.splitext(ibFileName)[0] + ".strings"
                print '  ' + stringsFileName
                original = merged = os.path.join(language, stringsFileName)
                old = original + '.old'
                new = original + '.new'
			    
                if os.path.isfile(original) and not language.endswith(developmentLanguage):
                    os.rename(original, old)
                    os.system('ibtool --export-strings-file %s %s' % (original, ibFilePath))
                    os.system('iconv -f UTF-16 -t UTF-8 "%s" > "%s"' % (original, new))
                    merge(merged, old, new)
                else:
                    os.system('ibtool --export-strings-file %s %s' % (original, ibFilePath))
                    os.rename(original, old)
                    os.system('iconv -f UTF-16 -t UTF-8 "%s" > "%s"' % (old, original))
                    
                if os.path.isfile(old):
                    os.remove(old)
                if os.path.isfile(new):
                    os.remove(new)

if __name__ == '__main__':
	argc = len(argv)
	if (argc <= 1 or 4 < argc):
		print 'Usage: %s path_to_source_directory [routine] [development_language]' % argv[0]
		quit()
	
	path = os.path.abspath(argv[1])
	routine = argv[2] if argc > 2 else 'NSLocalizedString'
	developmentLanguage = argv[3] if argc > 3 else 'en'
	localizeCode(path, routine)
	localizeInterface(path, developmentLanguage)

screenshot-finder.png

screenshot-runscript.png

@maxykato have you find any fixes for you?

For anyone having issues with iconv while converting your files. I recommend modifying the script to use vim instead.
That worked for me.