ios - Core Data Migration: Possible to delete old store except for a few specific objects? -

the new version of our app complete redo, different in every way. reading migration, think i'd fall heavy camp (added relationships), i'm not sure need of data , not sure have chops complex migration. being said, realized users can save favorite stories , i'd preserve of data (but not whole nsmo story entity different now). that's need, few pieces of data few nsmos.

i've got detection setup -isconfiguration:compatiblewithstoremetadata: , have deleted old store -removeitematurl: wort case scenario, there way fetch couple things before delete , build new objects?

yes, can stand old store old model , fetch data out of , manually insert new stack. delete old store afterwards. actual workflow be:

• new model separate file
• new store separate file (new file name)

then:

1. look old file name on disk. if doesn't exist stand stack
2. stand old stack.
3. stand new stack.
4. copy data old stack new stack.
5. save new stack.
6. release old stack , delete old store file disk.

no migration needed.

i added old model file. in psc method, detect if compatible , if not, stand old stack, initiating model , psc both pointing old 1 added , creating context. added old class files entity need , fetched favorites , worked! know can create new objects , insert new stack, what's best way save new stack , release old when done? still seem able fetch after removeitematurl. , app delegate best place this?

first, appdelegate not place this. create datacontroller subclasses nsobject. put core data code there , pass datacontroller around.

next, not looking migration state. looking files on disk nsfilemanager. if old file exists stand old store , new store, copy data over. remove old file.

to release old stack, set references (mom, psc , moc) nil. arc remove them memory.