I've wrote a xcode plugin to do this kind of job. Execute script is slow in xcode, so I did not choose to write s script to do it. Although writing Xcode plugin is kind of difficult, there is not official documentation, but after get used to it, it is fun to play with it.
Here is the link:
https://github.com/nanaimostudio/Xcode-Quick-Localization
Install:
- Build the project use Xcode.
Usage:
Select multiple line, press Option+Shift+D
if no selection, it will convert only current line.