Synchronizing with iOS

Calendar

Open the settings application.
Select Calendar.
Select Accounts.
Select Add Account.
Select Other as account type.
Select Add CalDAV account.
For server, type the domain name of your server i.e. example.com.
Open Advanced Settings
For server, type the domain name of your server and username i.e. example.com/remote.php/dav/principals/users/username/
Close Advanced Settings
Enter your user name and password.
Select Next.

Your calendar will now be visible in the Calendar application.

Catatan

Beginning with iOS 12 an SSL encryption is necessary. Therefore do not disable SSL (For this reason a certificate is required at your domain, https://letsencrypt.org/ will do).

Contacts

Open the settings application.
Select Contacts.
Select Accounts.
Select Add Account.
Select Other as account type.
Select Add CardDAV account.
For server, type the domain name of your server i.e. example.com.
Enter your user name and password.
Select Next.

You should now find your contacts in the address book of your iPhone.

Catatan

Beginning with iOS 12 an SSL encryption is necessary. Therefore do not disable SSL (For this reason a certificate is required at your domain, https://letsencrypt.org/ will do).

If it's still not working, have a look at Troubleshooting Contacts & Calendar or Troubleshooting Service Discovery.