Menu
Right now I use versioning to make any changes in a database. But it brings some problems. For example it's hard to merge a feature branch with a new db version into a master/dev where somebody also added a new version.
So my question: Is it safe to change db in a single xcdatamodel without adding new versions? I tried so and it works but everywhere on the internet I see warnings that you must not do that.
iOS9+.
I found this: https://stackoverflow.com/a/37264096/5328417 but it's without a proof
669
Core Data can typically perform an automatic data migration, referred to as lightweight migration. Lightweight migration infers the migration from the differences between the source and the destination managed object models.
The next time you need to store data, you should have a better idea of your options. Core Data is unnecessary for random pieces of unrelated data, but it's a perfect fit for a large, relational data set. The defaults system is ideal for small, random pieces of unrelated data, such as settings or the user's preferences.
A Core Data mapping model describes the transformations that are required to migrate data described by a source managed object model to the schema described by a destination model. When you make a new version of a managed object model, you need to migrate persistent stores from the old schema to the new.
As @pbasdf noted, since iOS 9 you can do a lightweight migration without adding any new model version. Source model (previous model version) is cached to store and used as a last ditch effort during lightweight migration.
I am using this feature in my own apps successfully. Although I was not able to find this documented. Just that WWDC video (18'15 Model Caching) mentioned. This is exactly the reason why Core Data is so mysterious sometimes..
55
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
