Question

I am developing an iOS application and i am using CoreData to persiste my data. The application is like iBooks, we can download a book, read a book, takes notes in the book,… and for this i have many entities in CoreData (NoteEntity,….).
Now i have a functionality witch is removing a book downloaded by the user ( the user can download many books and there are a functionality to delete a book ( to have spaces for example)). My question is, is there a simple way to remove all the objects in CoreData ( all the objects corresponding to the book deleted by the user) Thanks for your answers.

Answer 1

Create a “Cascade” delete relationship between the book and all objects associated with it.

From Core Data programming guide:

Relationship Delete Rules: A relationship’s delete rule specifies what
should happen if an attempt is made to delete the source object. Note
the phrasing in the previous sentence—”if an attempt is made…”. If a
relationship’s delete rule is set to Deny, it is possible that the
source object will not be deleted. Consider again a department’s
employees relationship, and the effect that the different delete rules
have.

…

Cascade:
Delete the
objects at the destination of the relationship. For example, if you
delete a department, fire all the employees in that department at the
same time.