86 lines
2.6 KiB
Swift
86 lines
2.6 KiB
Swift
//
|
|
// FetchedValueHolder.swift
|
|
// Passepartout
|
|
//
|
|
// Created by Davide De Rosa on 4/8/22.
|
|
// Copyright (c) 2022 Davide De Rosa. All rights reserved.
|
|
//
|
|
// https://github.com/passepartoutvpn
|
|
//
|
|
// This file is part of Passepartout.
|
|
//
|
|
// Passepartout is free software: you can redistribute it and/or modify
|
|
// it under the terms of the GNU General Public License as published by
|
|
// the Free Software Foundation, either version 3 of the License, or
|
|
// (at your option) any later version.
|
|
//
|
|
// Passepartout is distributed in the hope that it will be useful,
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
// GNU General Public License for more details.
|
|
//
|
|
// You should have received a copy of the GNU General Public License
|
|
// along with Passepartout. If not, see <http://www.gnu.org/licenses/>.
|
|
//
|
|
|
|
import Foundation
|
|
import CoreData
|
|
import Combine
|
|
|
|
public class FetchedValueHolder<V>: NSObject, ValueHolder, NSFetchedResultsControllerDelegate {
|
|
@Published public var value: V
|
|
|
|
private let controller: NSFetchedResultsController<NSFetchRequestResult>
|
|
|
|
private let mapping: ([NSFetchRequestResult]) -> V?
|
|
|
|
public convenience init(
|
|
context: NSManagedObjectContext,
|
|
request: NSFetchRequest<NSFetchRequestResult>,
|
|
mapping: @escaping ([NSFetchRequestResult]) -> V?,
|
|
initial: V
|
|
) {
|
|
let controller = NSFetchedResultsController(
|
|
fetchRequest: request,
|
|
managedObjectContext: context,
|
|
sectionNameKeyPath: nil,
|
|
cacheName: nil
|
|
)
|
|
self.init(controller: controller, mapping: mapping, initial: initial)
|
|
}
|
|
|
|
public init(
|
|
controller: NSFetchedResultsController<NSFetchRequestResult>,
|
|
mapping: @escaping ([NSFetchRequestResult]) -> V?,
|
|
initial: V
|
|
) {
|
|
self.controller = controller
|
|
self.mapping = mapping
|
|
value = initial
|
|
super.init()
|
|
|
|
controller.delegate = self
|
|
do {
|
|
try controller.performFetch()
|
|
} catch {
|
|
pp_log.error("Unable to perform initial fetch: \(error)")
|
|
}
|
|
mapResults()
|
|
}
|
|
|
|
public func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
|
|
mapResults()
|
|
}
|
|
|
|
private func mapResults() {
|
|
guard let results = controller.fetchedObjects else {
|
|
return
|
|
}
|
|
pp_log.verbose("Results: \(results)")
|
|
guard let newValue = mapping(results) else {
|
|
return
|
|
}
|
|
value = newValue
|
|
}
|
|
}
|