So I got a new iPhone, and wanted to copy all the music on my old iPhone to it. I was stupid and didn’t make a playlist when I added the music so I had no way of doing it automatically. Or so I thought. Fortunately it’s ridiculously simple to do.
Right click on the Music folder on your old iDevice and click export and save the file somewhere, then click File -> Library -> Import Playlist and open the file you created earlier. You might need to make sure you select a local playlist before importing so it doesn’t import to your phone, but I’m not sure on that.
You can now sync your new playlist with your new phone and get all the songs you had on the old one.