Error in Terminal while trying to generate Localizable.strings file

I followed the instructions, but my Terminal gave me this error:

xcode-select: error: tool 'genstrings' requires Xcode, but active developer directory '/Library/Developer/CommandLineTools' is a command line tools instance

Why does this occur? And what’s the fix?

It appears Xcode hasn’t installed its commandline tools yet. Usually this happens during first run.

You can kick it off manually by executing this in Terminal:

 xcode-select --install

Note that there are two dashes in that instruction.

Then follow the installer prompts when they appear.

I installed the Command Line Tools, but still got the same error.

Update: I just created Localizable.strings manually to continue with the chapter.