Using unmanaged core data properties as section identifiers

Question

CraigH2013 OP

Created Aug ’21

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Let's say I have a Person entity in my core data model that has a name attribute of type String.

I want to use a sectioned fetch request to list my Person entities sectioned by the first letter of their name.

I wrongly assumed I could just add a property to my NSManagedObject subclass and use it in a sectioned fetch request as follows

extension Person {
    var firstLetterOfName: String {
        // get the first letter
    }
}

@SectionedFetchRequest(
    sectionIdentifier: \.firstLetterOfName,
    sortDescriptors: [
        SortDescriptor(\.name, order: .forward)
    ])
var people: SectionedFetchResults<String, Person>

However, I end up with an uncaught exception NSUnknownKeyException

How can I define this property in a way that I can use it in the section identifier?

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Answer 1

CraigH2013 OP

Aug ’21

Turns out I just needed to add @objc to my declaration of the firstLetterOfName property

extension Person {
    @objc var firstLetterOfName: String {
        // get the first letter
    }
}

0