iOS supports CalDAV natively. Just follow the instructions at https://www.fastmail.com/help/clients/iphone.html https://www.fastmail.com/help/clients/iphone.htm

iOS supports CalDAV natively. Just follow the instructions at https://www.fastmail.com/help/clients/iphone.html https://www.fastmail.com/help/clients/iphone.html (scroll down for calendar section).