I am working on an iPhone app that uses a subclass of UIManagedDocument and stores its documents on iCloud.
It was all working fine until I changed my core data model / scheme (adding a new model version - like I had several times in the past few weeks). I added a new property and changed the data type of one of the existing properties.
Now when I run my app I don't seem to be able to load my documents with UIManagedDocument's -openWithCompletionHandler:.
I can create new documents and read/write those.
If I change the data model version back 1 then I am able to read the existing docs, but not the new ones.
From what I understand I am only do lightweight migrations to the data model and UIManagedDocument is supposed to handle that right?
Any advice would be greatly appreciated!
In a subclass of UIManagedDocument you may want to try overriding managedObjectModel like so:
- (NSManagedObjectModel *)managedObjectModel
{
NSString *path = [[NSBundle mainBundle] pathForResource:@"<ModelNameHere>" ofType:@"momd"];
NSURL *momURL = [NSURL fileURLWithPath:path];
NSManagedObjectModel *managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:momURL];
return managedObjectModel;
}
Given below is based on my understanding:
NOTE - I haven't tried it for iCloud but I have tested it for non-icloud and seems ok.
UIManagedDocument configures the managedObjectModel and a Persistent Store Coordinator by itself
When migration needs to be done, just set the UIManagedDocument's persistentStoreOptions
//Note - In this example, managedDocument is a UIManagedDocument property
self.managedDocument.persistentStoreOptions = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES], NSMigratePersistentStoresAutomaticallyOption,
[NSNumber numberWithBool:YES], NSInferMappingModelAutomaticallyOption, nil];
Refer:
来源：https://stackoverflow.com/questions/8667149/uimanageddocument-migrate-data-model