Using SwiftUI with Core Data

user_196678 0
Viewed 2682

SwiftUI tables require a binding to an array storing the entirety of your model objects in memory. For small datasets, the tradeoff of convenience for performance makes sense. But for datasets with tens/hundreds of thousands of values, the old-school approach to rendering tables through queries to a datasource still seems like the way to go. (Consider a simple dictionary/thesaurus app.).

Is there a way to implement dataSource-style/CoreData-backed tables within SwiftUI?

swiftui core-data
2 Answers

List does not require an Array. The Data must conform to the RandomAccessCollection protocol. This could also be your NSFetchedResultsController.

extension List {
    /// Creates a List that computes its rows on demand from an underlying
    /// collection of identified data.
    @available(watchOS, unavailable)
    public init<Data, RowContent>(
        _: Data,
        selection _: Binding<Selection>?,
        rowContent _: @escaping (Data.Element.IdentifiedValue) -> RowContent
    ) where Content == ForEach<Data, HStack<RowContent>>,
        Data: RandomAccessCollection,
        RowContent: View,
        Data.Element:
        Identifiable

    /// Creates a List that computes its rows on demand from an underlying
    /// collection of identified data.
    @available(watchOS, unavailable)
    public init<Data, RowContent>(
        _: Data,
        selection _: Binding<Selection>?,
        action _: @escaping (Data.Element.IdentifiedValue) -> Void,
        rowContent _: @escaping (Data.Element.IdentifiedValue) -> RowContent
    ) where Content == ForEach<Data, Button<HStack<RowContent>>>,
        Data: RandomAccessCollection,
        RowContent: View, Dat
}
user_37166120

I think that's the reason of using ForEach() for loops in SwiftUI, so the view can control how many elements needs to instantiate to fill the screen.

And the Array from a Core Data fetch request probably doesn't contains all the objects in memory, they only get instantiated when they are accessed.

user_8553660
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