What is the correct way to delete a UIManagedDocument? - core-data

Question

I can't seem to find any reliable documentation that explains the correct procedure for deleting a UIManagedDocument, and in particular one where the iCloud options have been turned ON.
I understand that this option would delete the file at this fileURL. And this would appear to be fine if iCloud is not being used.
[[NSFileManager defaultManager] removeItemAtURL:fileURL error:&error];
If iCloud is being used then CoreData creates files all over the place, including in /Document/CoreDataUbiquitySupport and in the iCloud /CoreData folder. So in this case is it up to me to call removeUbiquitousContentAndPersistentStoreAtURL for each store in the UIManagedDocument prior to calling [NSFileManager removeItemAtURL]. If so is this documented somewhere ?
[NSPersistentStoreCoordinator removeUbiquitousContentAndPersistentStoreAtURL:storeURL
options:#{NSPersistentStoreUbiquitousContentNameKey:fileName,
NSMigratePersistentStoresAutomaticallyOption:#YES,
NSInferMappingModelAutomaticallyOption:#YES,
NSSQLitePragmasOption:#{ #"journal_mode" : #"DELETE" }}
error:&error];

Answer 1

Here is my two cents on the issue. I tried what dtrotzjr recommended and didn't have a whole lot of success. It seems that removeUbiquitousContentAndPersistentStoreAtURL:options:error: is great for clearing out data in a UIManagedDocument, but the Logs folder is still there and so are the remnants of the file I'm trying to delete. Here is a simpler method for completely deleting a UIManagedDocument from iCloud or Local Docs:
+ (void)deleteDocumentURL:(NSURL *)url{
//if we have an iCloud Document, remove it from the UbiquitouseKeyValueStore
if ([self isiCloudURL:url]) {
[[NSUbiquitousKeyValueStore defaultStore] removeObjectForKey:[url lastPathComponent]];
}
//do the delete on another thread
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
NSFileCoordinator *coordinator = [[NSFileCoordinator alloc] initWithFilePresenter:nil];
NSError *coordinationError;
[coordinator coordinateWritingItemAtURL:url
options:NSFileCoordinatorWritingForDeleting
error:&coordinationError
byAccessor:^(NSURL *newURL) {
NSError *removeError;
//code for performing the delete
[[NSFileManager defaultManager] removeItemAtURL:newURL error:&removeError];
//if we have an iCloud file...
if ([self isiCloudURL:url]) {
//remove log files in CoreData directory in the cloud
NSURL *changeLogsURL = [[self urlForiCloudLogFiles] URLByAppendingPathComponent:[url lastPathComponent]];
[[NSFileManager defaultManager] removeItemAtURL:changeLogsURL error:&removeError];
}
}];
});
}
This is pretty much the code from Stanford's CS193 course 2012 + the delete for the changeLogs folder and it works on local and iCloud docs. Please let me know if you see any issues with performing the delete this way.

Answer 2

For iCloud core-data content you want to call the static method removeUbiquitousContentAndPersistentStoreAtURL:options:error: on the NSPersistentStoreCoordinator class, then call removeItemAtURL:error:
See deleteManagedDocumentWithIdentifier: in my APManagedDocument project. This is on the ubiquitous_experiment branch which I am currently working on finalizing before I merge it back down to the master branch.