MoreData

Helpers for integrating Core Data with a modern app, using Swift enums, Combine publishers, and structured concurrency.

MoreData is designed to streamline working with Core Data in Swift projects. Core Data is a powerful and mature framework, but is clunky and not Swift-native. This collection of protocols and utilities simplify fetching, filtering, and observing Core Data entities using a more reactive and Swift-friendly approach.

Features

• Filtering: Simplify the creation and combination of NSPredicate objects used to specify filter criteria.
• Sorting: Simplify the creation and combination of NSSortDescriptor objects for sorting query results.
• @FetchableRequest Property Wrapper: A better way to power SwiftUI views backed by Core Data.
• FetchableResultsPublisher: Reactive fetching and observing of Core Data entities using Combine.
• CoreDataPersistenceController: Wrapper for boilerplate Core Data setup, providing easy initialization for common patterns.

Installation

Swift Package Manager

To integrate MoreData into your project using Swift Package Manager, add the following dependency to your Package.swift file:

dependencies: [
    .package(url: "https://github.com/ChrisLaganiere/MoreData.git", from: "1.0.0")
]

Usage

Fetchable Protocol

The Fetchable protocol simplifies the process of fetching Core Data entities. Conform your NSManagedObject subclasses to Fetchable and use the provided helper methods to perform fetches.

Example

import CoreData
import MoreData

class Person: NSManagedObject {
    @NSManaged var name: String?
    @NSManaged var age: Int16

    static var entityName: String {
        return "Person"
    }
}

// MARK: Fetchable
extension Person: Fetchable {
    typealias Filter = PersonFilter
    typealias Sort = PersonSort

    static var entityName: String {
        "Person"
    }
}

let moc: NSManagedObjectContext = // your managed object context
let kyles = try? Person.all(predicate: NSPredicate(format: "%K CONTAINS[cd] %@", #keyPath(Person.name), "Kyle"), moc: moc)

Filtering Protocol

The Filtering protocol allows you to define reusable and composable filters for Core Data queries.

Example

enum PersonFilter: Filtering {
    case nameContains(String)
    case ageGreaterThan(Int)

    var predicate: NSPredicate? {
        switch self {
        case .nameContains(let name):
            return NSPredicate(format: "name CONTAINS[cd] %@", name)
        case .ageGreaterThan(let age):
            return NSPredicate(format: "age > %d", age)
        }
    }
}

let kylesFilter = PersonFilter.nameContains("Kyle")
let kyles = try? Person.all(matching: kylesFilter, moc: moc)

Sorting Protocol

The Sorting protocol allows you to define Swift-friendly sort criteria for Core Data fetch results.

Example

enum PersonSort: Sorting {
    /// Sort alphabetically, A-Z
    case nameAscending(Bool)

    var sortDescriptors: [NSSortDescriptor] {
        switch self {
        case .nameAscending:
            return [NSSortDescriptor(key: "name", ascending: true)]
        }
    }
}

let kyles = try? Person.all(matching: .nameContains("Kyle"), sortedBy: .nameAscending, moc: moc)

FetchableResultsPublisher

The FetchableResultsPublisher class provides a Combine-based interface to fetch and observe Core Data entities, making it easy to integrate with SwiftUI or other reactive UI frameworks.

Example

import Combine
import CoreData
import MoreData

let kylePublisher = FetchableResultsPublisher<Person>(
    filter: .nameContains("Kyle"),
    sort: .nameAscending,
    moc: moc
)

kylePublisher.fetchedObjectsPublisher
    .sink { fetchedObjects in
        // Update your UI with the fetched objects
    }
    .store(in: &cancellables)

@FetchableRequest Property Wrapper

The @FetchableRequest property wrapper simplifies the process of retrieving and observing NSManagedObject entities that conform to the Fetchable protocol within SwiftUI views. It provides a declarative interface for fetching Core Data entities while integrating seamlessly with SwiftUI's state-driven UI updates.

Features

• Declarative Fetching: Easily fetch entities based on filter and sort criteria directly within your SwiftUI views.
• Reactive Updates: Automatically updates your view when the underlying Core Data changes.
• Dynamic Querying: Modify filter and sort criteria dynamically, and the results will update automatically.

Usage

To use @FetchableRequest, simply declare it in your SwiftUI view, specifying the entity type, filter, and sort criteria. The fetched results will be automatically available to your view.

import SwiftUI
import MoreData

struct PersonListView: View {

    @FetchableRequest(
        entity: Person.self,
        filter: .none,
        sort: .nameAscending
    ) var people: FetchedResults<Person>

    @State private var showKylesOnly = false

    var body: some View {
        VStack {
            Toggle("Show Kyles Only", isOn: $showKylesOnly)
                .padding()

            List(people) { person in
                VStack(alignment: .leading) {
                    Text(person.name ?? "Unknown Name")
                    Text("Age: \(person.age)")
                        .font(.subheadline)
                        .foregroundColor(.secondary)
                }
            }
            .navigationTitle(showKylesOnly ? "Kyles" : "All People")
        }
        .onChange(of: showKylesOnly) { newValue in
            if newValue {
                _people.filter = .nameContains("Kyle")
            } else {
                _people.filter = .none
            }
        }
    }
}

In this example, the list dynamically updates based on the toggle state, switching between showing all people or only people named Kyle.

Background

Core Data is a long-serving Apple framework reducing the amount of code you need to write for a robust, persistent entity graph.

Core Data entities are not thread-safe and should only be used in the context where they were fetched.

License

This project is licensed under the MIT License.

Acknowledgements

Written by: Chris L 🫎

Contributions are welcome! If you have any ideas, suggestions, or bug reports, please open an issue or submit a pull request.