lightweight migrations swift2 xcode7

2
votes

I have to add one entity in my coreData project but I can't understand how to do the lightweight migrations in swift. I'm stuck at point 8, how can i traslate that code from objective-c to swift? Thank you!

1-Open your .xcdatamodeld file

2-click on Editor

3-select Add model version...

4-Add a new version of your model (the new group of datamodels added)

5-select the main file, open file inspector (right-hand panel)

6-and under Versioned core data model select your new version of data model for current data model 7-THAT'S NOT ALL ) You should perform so called "light migration".

8-Go to your AppDelegate and find where the persistentStoreCoordinator is being created

9-Find this line if (![_persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType configuration:nil URL:storeURL options:nil error:&error])

10-Replace nil options with @{NSMigratePersistentStoresAutomaticallyOption:@YES, NSInferMappingModelAutomaticallyOption:@YES} (actually provided in the commented code in that method)

11-Here you go, have fun!

1
iosswiftcore-data-migration

1 Answers

8
votes

In a template project the line that create the persistent store is

if coordinator!.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: nil, error: &error) == nil {

To perform a lightweight migration you have to pass the following dictionary as options argument, instead of nil:

[NSMigratePersistentStoresAutomaticallyOption: true, NSInferMappingModelAutomaticallyOption: true]