iOS contains both a CalDAV and a CardDAV client for quite a few versions. It is one of the best clients out there.

Supported features

Not supported:

Technical details

Very incomplete list of user agent's we've come across:

DataAccess/1.0 (8J2) iOS/6.0 (10A403) dataaccessd/1.0 DAVKit/4.0 (728.4); iCalendar/1 (42.1); iPhone/3.1.3 7E18


The client will ask for the following additional properties on principals when setting up carddav.

When setting up caldav:

The client will perform the following PROPFIND request on the addressbook-home-set:

<?xml version="1.0" encoding="UTF-8"?>
<A:propfind xmlns:A="DAV:">
    <E:bulk-requests xmlns:E=""/>
    <D:max-image-size xmlns:D="urn:ietf:params:xml:ns:carddav"/>
    <D:max-resource-size xmlns:D="urn:ietf:params:xml:ns:carddav"/>
    <C:me-card xmlns:C=""/>
    <C:push-transports xmlns:C=""/>
    <C:pushkey xmlns:C=""/>

And the following on a single addressbook:

<?xml version="1.0" encoding="UTF-8"?>
<A:propfind xmlns:A="DAV:">
    <C:getctag xmlns:C=""/>

It will use the addressbook-multiget REPORT to fetch contents of cards.

On the calendar-home-set it will request:

On calendars it may use REPORT to find all events within a certain time range:

<x0:calendar-query xmlns:x0="urn:ietf:params:xml:ns:caldav" xmlns:x1="DAV:">
        <x1:getetag />
        <x1:resourcetype />
        <x0:comp-filter name="VCALENDAR">
            <x0:comp-filter name="VEVENT">
                <x0:time-range start="20100420T150000Z" />

The last report is only used to find out of any event changed. The calendar-multiget report is used to download the actual changes:

<x0:calendar-multiget xmlns:x0="urn:ietf:params:xml:ns:caldav" xmlns:x1="DAV:">
        <x1:getetag />
        <x0:calendar-data />

Base urls in iOS6

It was reported that iOS switches to extremely buggy behavior if the CardDAV server is not running on the root of the server, more specifically.. when the user sets up the CardDAV server and the 'server' they fill in is not just a domain name, iOS breaks severely.

If you must have a carddav server that's not running off the root, you can workaround this by setting up a 'well-known' endpoint for CardDAV, as described in ServiceDiscovery.

Base urls in iOS7

iOS7 also has issues with servers not running on a root domain, although the problem appears to have changed a bit in nature (need more details).

Setting up the Cal and CardDAV server by using a full principal url seems to almost always fix these problems.

This issue also appeared in very old iOS versions (iOS 3).

Directory support

iOS has support for a global read-only directory. iOS does not allow simply browsing through the directory, it's used for searching only (using the addressbook-query REPORT).

SabreDAV does have (very minimal) support for CardDAV directory.

Encoding of HTTP/1.1 200 Ok

Apparently older iOS versions (1.4.2) require HTTP/1.1 200 Ok to be encoded in uppercase (OK rather than Ok). This is fixed in SabreDAV version 1.5.3.