Open Radar

 
Summary:

If an iCloud user deletes the contents of a container, subsequent attempts to access the container result in an NSPersistentStoreCoordinator error. 

Steps to Reproduce:

1. Delete contents of container (on device -- Settings > iCloud > Storage & Backup > Manage Storage; or on Lion -- System Preferences -> iCloud -> Manage). 
2. Try to access container (NSPersistentStoreCoordinator addPersistentStoreWithType:configuration:URL:options:error:)

Expected Results:

User can access iCloud data. 

Actual Results:

-NSPersistentStoreCoordinator addPersistentStoreWithType:configuration:URL:options:error:: CoreData: Ubiquity: Error attempting to read ubiquity root url: file://localhost/private/var/mobile/Library/Mobile%20Documents/./data/. Error: Error Domain=LibrarianErrorDomain Code=1 "The operation couldn’t be completed. (LibrarianErrorDomain error 1 - Unable to initiate item download.)" UserInfo=0x176000 {NSURL=file://localhost/private/var/mobile/Library/Mobile%20Documents/./data/, NSDescription=Unable to initiate item download.}

The only known workaround is to change the App ID or the name of the iCloud container. 

Regression:

Notes:

For more information: 
http://stackoverflow.com/questions/8021753/crash-when-adding-persistent-store-icloud-enabled-in-app-delegate

This has been reproduced on an app under development. I haven't tried it on a released app (because obviously I don't want to release with this bug). But even if it only affects apps under development, it's a serious problem because sometimes developers need to delete the contents of their iCloud container.