Fetch them into memory using a single fetch request and then loop through them.
Let's say you have a list of user IDs for users that you need to delete.
I'll start out by giving you the big picture of how Cora Data works.
Afterward, we'll take a look at Apple's default implementation of Core Data, and then I'll show you how we can easily improve on it. Xcode provides a visual tool called an entity data model (or just "data model" for short) that you can use to model your app's entities.
If this it is not the case you can find very good tutorials on the Tim Roadely’s blog or on the Ray Wenderlich’s blog.
If you have already work with the Core Data framework you probably found this hard to learn.
In this weekly blog series, How to Unleash Your Inner App Developer, I will take you, the non-programmer, step-by-step through the process of creating apps for the i Phone, i Pod touch, and i Pad.
If you are using Core Data, need to change your database scheme but Core Data cannot infer the changes on its own.
When you start you have to understand what is the role of each components (NSManaged Object, NSManaged Object Context, NSManaged Object Model, NSPersistent Store Coordinator, etc.) and how they work/communicate between them.
Once you understand the principle, you notice that the code is not easy to do too.
Also I used the if #available(i OS 9.0, *) so that i OS 9 devices can take advantage of the speedy code for it.
Then run my tweaked code base your suggestions to support older i OS. Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).