Swift CoreData using predicates with Array

Question

I need to keep array of Strings in CoreData and later on use predicates for filtering data for that array.

According to this post field type Transformable (with custom class [String]) does the trick and I can properly save array of Strings: How to save Array to CoreData?

However, I can't use predicates for this fields. Specifically, my goal is to find all items where at least one item in saved array matches pattern.

So, back to question: is there a good way of storing array in CoreData so that I can apply predicates for it later on?

Possible duplicate of stackoverflow.com/questions/6104566/…. — Martin R
– Martin R, Commented Oct 6, 2018 at 10:47
Yes, that post somehow answers. I can't use it however since not familiar with Objective-C — Олександр Бабіч
– Олександр Бабіч, Commented Oct 6, 2018 at 11:05
Another possible solution - to create another Entity with possible array values and create relations between my object and new entities. — Олександр Бабіч
– Олександр Бабіч, Commented Oct 6, 2018 at 11:07

Witek Bobrowski · Accepted Answer · 2021-07-27 17:20:04Z

2

Found an appropriate solution for CoreData

Don't put array as Transformable field in Entity

Create separate Entity with a single field, use that entities instead of array.
Create relation between main Entity and Array replacement Entity.
During runtime: find CoreObject of array Entity using predicate:

NSPredicate(
    format: "%K = %@", #keyPath(YourArrayEntity.onlyField),
    matchingString
)

Use predicates for searching your main entities

NSPredicate(
    format: "ANY %K == %@",
    #keyPath(YourMainEntity.relationToArrayEntity), 
    arrayEntityFoundInPreviousStep
)

edited Jul 27, 2021 at 17:20

Witek Bobrowski

4,3191 gold badge25 silver badges39 bronze badges

answered Oct 6, 2018 at 12:58

Олександр Бабіч

1,4722 gold badges22 silver badges30 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Swift CoreData using predicates with Array

1 Answer 1

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related