Core Data Database Migration

First, lightweight migration

I. Suitable for the scene

Simple addition of a new attribute

Removal of an attribute

A non-optional attribute becoming optional

An optional attribute becoming non-optional, and defining a default value

Renaming an entity or property

II. How to Do

1. Set Persistent Store:

Nsdictionary *persistentstoreoptions = @{nsmigratepersistentstoresautomaticallyoption: @YES,

Nsinfermappingmodelautomaticallyoption: @YES};

PersistentStore = [_persistentstorecoordinator addpersistentstorewithtype:nssqlitestoretype configuration:nil URL: Storeurl options:persistentstoreoptions error:&addstoreerror];

2. Add a version to Database.xcdatamodel

Select Database.xcdatamodel, Editor, Add Model Version, and then set which data model file for the current database is the right one.

3. This will be done. So easy and simple. And this kind of migration mode, occupy most of database data migration application scenario.

Second, multiple Passes

This technology, I have not yet encountered the need to use its scene, so did not take the time to study. As for how to deal with, can refer to a very good blog, http://www.cnblogs.com/liyufeng2013/p/3782351.html

Apple official doc:https://developer.apple.com/library/prerelease/ios/documentation/cocoa/conceptual/ Coredataversioning/articles/vmmappingoverview.html#//apple_ref/doc/uid/tp40004399-ch5-sw1

Core Data Database Migration