Apple iCal's "Delegation" tab -- disabled checkboxes?

I am trying to access a CalDAV account in iCal and everything works fine except for the Delegation tab. I can see the account(s) I have access to (including the correct read/write properties), but the checkboxes are disabled and the calendars cannot be selected. Has anyone seen this before & know w开发者_JAVA百科hat the cause is?

This is a custom CalDAV implementation, so it is likely due to a disconnect between what iCal expects and what our server is sending -- but there are no error/warning messages in the console to indicate what the problem might be.

Any advice would be appreciated.

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iCal queries the permissions and methods available on the server. To query the permissions on a collection resource you will need to have the DAV::read-current-user-privilege-set permission. Assuming iCal can read the permissions it will be looking for the DAV::read permission for reading and the DAV::bind, DAV::unbind and DAV::write permissions to indicate the ability to write.

The best way to debug this is probably to read RFC3744 about half a dozen times, interspersed with using iCal against a working server and sniffing the TCP communication as it does it. A good way is to use some kind of man-in-the-middle proxy so you can sniff the communication with (e.g.) Mobile Me or iCloud.

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In my limited experience, this happens when the account used for sharing is functional (not personal) in Microsoft Exchange Server 2010. An example, where two of three are functional:

I do use various CalDAV implementations but have never encountered the same limitation, so this may be not a good answer. Also Exchange Web Services (EWS) for calendaring and delegation are probably not comparable to CalDAV. Still, it's food for thought.

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The Debug menu of iCal 5.x offers CalDAV logging options.

To enable that menu, you could use the Secrets preference pane.