If you want to use the baikal CalDav Server together with iOS you might notice that this does not work optimally. For me, the calendar was not recognized correctly and also not synchronized. The reason for this is that a few redirects on the part of Apache were missing.

RewriteEngine on
...
Redirect 301 /.well-known/carddav https://domain.ch/baikal/html/card.php
Redirect 301 /.well-known/caldav  https://domain.ch/baikal/html/cal.php
Redirect 301 /.well-known/webdav  https://domain.ch/baikal/html/dav.php

After pasting the above lines and restarting Apache, the calendar worked fine! These lines are from hier

The following calendar line was used for this on iOS:

https://domain.ch/baikal/html/cal.php/calendars/username