Unicode characters and webservices always create one or the other problem for me 😉 Working on PlannerX backend was not any different. Spent some good hours fixing Unicode / UTF-8 related issues.
And while I was searching for some solutions, I found an excellent “PHP UTF-8 Cheat Sheet” by Nick Nettleton of DropSend. I highly recommend it if you are going to do anything with PHP and Unicode!
And BTW, don’t use Base64 encoding with UTF-8. It will not work!