iOS supports CalDAV and CardDAV protocols natively within the settings menu :
- Go to Settings > Mail > Accounts > Add Account.
- Select Other, then choose Add CalDAV Account (for calendar) or Add CardDAV Account (for contacts).
- Server:
dav.privateemail.com. - Username: Your full Hostaday email address.
- Password: Your mailbox password.
- Click Next to verify and save the account .