On 4, Nov, 2011, at 03:06 PM, Roland King wrote:
>
> On Nov 4, 2011, at 1:41 PM, Martin Hewitson wrote:
>
>>
>> On 4, Nov, 2011, at 02:01 AM, Roland King wrote:
>>
>>>
>>>
>>>
>>>
>>>> So, can I conclude from this that iCloud and core-data only works with SQL
>>>> store? The WWDC video hints at this, but was not explicit.
>>>>
>>>
>>> Not so. I have a core data app running using icloud and an XML store. This
>>> is ios by the way and the store is not incremental, it's just being treated
>>> as a blob which is fully synced each time but it's small so that's ok.
>>>
>>> Definitely if you want the incremental log style store you have to use SQL
>>> but in general core data in iCloud will let you use whatever you like.
>>
>> I hadn't realised that I had made a choice. How does one choose an
>> incremental store as opposed to a blob? Any pointers how you got your
>> core-data iCloud app working would be greatly appreciated!
>
> Those two keys you add when you open the persistent store,
> NSPersistentStoreUbiquitousContentNameKey and
> NSPersistentStoreUbiquitousContentURLKey are the ones which tell Core Data
> you're using the log file based core data (only available with SQLite). So
> with that store, the actual SQLite database isn't in the cloud, it's kept
> local, but a log file directory is created which is in the cloud and deltas
> are synched up there. The idea is that each client just brings down the log
> files and updates the database at a record level. Those keys only mean
> anything with the SQLite store, which may be why you're having issues with
> migration. I don't use any of those keys, I just have my store as a local
> file which is synched wholesale.
>
> For your original mail, you want to migrate to SQLLite and then also migrate
> to iCloud. I don't know if you can do that easily in one step. If I were
> looking at this I would probably think of creating a new SQLLite store for
> the migration, empty, opening the old local XML store and then migrating the
> objects over with code. Whether you choose to make the new SQLite store local
> and then migrate it up to iCloud or make it in the cloud and then update it
> is a question I don't have a good answer to, I'm still a little confused by
> how the initial log files get magically created when you migrate a document
> to iCloud, I'm definitely missing a piece of information somewhere.
I think I've achieved this migration step with code like this:
NSURL *oldURL = [NSURL fileURLWithPath:[applicationSupportDirectory
stringByAppendingPathComponent:oldStoreName]];
NSURL *newURL = [NSURL fileURLWithPath:[applicationSupportDirectory
stringByAppendingPathComponent:storeName]];
persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc]
initWithManagedObjectModel:mom];
if ([fileManager fileExistsAtPath:[oldURL path]]) {
NSError *error = nil;
NSPersistentStore *store = [persistentStoreCoordinator
addPersistentStoreWithType:NSXMLStoreType
configuration:nil
URL:oldURL
options:options
error:&error];
if (!store){
[[NSApplication sharedApplication] presentError:error];
[persistentStoreCoordinator release], persistentStoreCoordinator = nil;
return nil;
}
// now add iCloud options
[options setObject:storeName
forKey:NSPersistentStoreUbiquitousContentNameKey];
NSURL *contentURL = [[NSFileManager defaultManager]
URLForUbiquityContainerIdentifier:containerID];
[options setObject:contentURL
forKey:NSPersistentStoreUbiquitousContentURLKey];
[options setObject:[NSNumber numberWithBool:YES]
forKey:NSValidateXMLStoreOption];
// migrate it
store = [persistentStoreCoordinator migratePersistentStore:store toURL:newURL
options:options withType:NSSQLiteStoreType error:&error];
if (error) {
[NSApp presentError:error];
return nil;
}
// archive old store
[fileManager moveItemAtURL:oldURL toURL:[oldURL
URLByAppendingPathExtension:@"xml"] error:&error];
if (error) {
[NSApp presentError:error];
}
} else {
// add iCloud
[options setObject:storeName
forKey:NSPersistentStoreUbiquitousContentNameKey];
NSURL *contentURL = [[NSFileManager defaultManager]
URLForUbiquityContainerIdentifier:containerID];
[options setObject:contentURL
forKey:NSPersistentStoreUbiquitousContentURLKey];
// make a new persistent store coordinator
if (![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType
configuration:nil
URL:newURL
options:options
error:&error]){
[[NSApplication sharedApplication] presentError:error];
[persistentStoreCoordinator release], persistentStoreCoordinator = nil;
return nil;
}
}
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Martin Hewitson
Albert-Einstein-Institut
Max-Planck-Institut fuer
Gravitationsphysik und Universitaet Hannover
Callinstr. 38, 30167 Hannover, Germany
Tel: +49-511-762-17121, Fax: +49-511-762-5861
E-Mail: [email protected]
WWW: http://www.aei.mpg.de/~hewitson
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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