There's a couple of lessons to be learned from this article by Damien Laughton. Just because something worked when you developed it, doesn't mean it'll work forever and test on multiple, real devices not just the latest and greatest phone that you personally use.
I mentioned Apple's guidance on CloudKit and GDPR a few weeks ago and hot on the heels of that, Artur Grigor is here with a useful library to help you export, or delete all data stored for a user from the CloudKit back end. This should make your job a bit easier!
There's no animation with the default tab bar, but should there be? I love this subtle animation from Jille van der Weerd, so here it is along with the code to implement it.
Every time someone tells me about their policy on self documenting code over comments, I think exactly what Graham Lee has written down here.