Question: When I try to get the identifier of an EKEvent, all I get is a nil value. Since in iOS5 EKEvent is a subclass of EKCalendarItem, I figured I might be able to get the EKCalendarItem's UUID, but that returns nil as well. 

Every now and then I also get this error while trying to access the identifier or UUID property: 

```
CADObjectGetInlineStringProperty failed fetching uniqueID for EKPersistentEvent with error Error Domain=NSMachErrorDomain Code=268435459 "The operation couldn’t be completed. (Mach error 268435459 - (ipc/send) invalid destination port)"

```

I've been stuck on this problem for quite some time now, but figured it would be iOS5 beta related. But since we're now at iOS5, it's still not working.

Answer: 
Just going through this problem, turnout the `eventIdentifier` will be null before commit to database, 
so you need a commit:`YES` in the saveEvent function `[self.eventStore saveEvent:event span:EKSpanThisEvent commit:YES error:&error];` 

After that, you can get the eventIdentifier. 

My fault was pass a NO to commit: parameter.
The EKEvent eventIdendifier isn't generated until the event is saved. You can access/store the eventIdentifier after you've saved the event to the EKEventStore

```
    [store saveEvent:event span:EKSpanThisEvent error:&err];
    NSString *eventIdentifier = event.eventIdentifier;

```