Implementation of "Automatic Lightweight Migration" for Core Data (iPhone)
- by RickiG
Hi
I would like to make my app able to do an automatic lightweight migration when I add
new attributes to my core data model.
In the guide from Apple this is the only info on the subject I could find:
Automatic Lightweight Migration
To request automatic lightweight
migration, you set appropriate flags
in the options dictionary you pass in
addPersistentStoreWithType:configuration:URL:options:error:.
You need to set values corresponding
to both the
NSMigratePersistentStoresAutomaticallyOption
and the
NSInferMappingModelAutomaticallyOption
keys to YES:
NSError *error;
NSURL *storeURL = <#The URL of a persistent store#>;
NSPersistentStoreCoordinator *psc = <#The coordinator#>;
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
[NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil];
if (![psc addPersistentStoreWithType:<#Store type#>
configuration:<#Configuration or nil#> URL:storeURL
options:options error:&error]) {
// Handle the error.
}
My NSPersistentStoreCoordinator is initialized in this way:
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator {
if (persistentStoreCoordinator != nil) {
return persistentStoreCoordinator;
}
NSURL *storeUrl = [NSURL fileURLWithPath: [[self applicationDocumentsDirectory] stringByAppendingPathComponent: @"FC.sqlite"]];
NSError *error = nil;
persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel:[self managedObjectModel]];
if (![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeUrl options:nil error:&error]) {
NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
abort();
}
return persistentStoreCoordinator;
}
I am having trouble seeing where and how I should add the Apple code to get the Automatic Lightweight Migration working?
