81 lines
2.6 KiB
Swift
81 lines
2.6 KiB
Swift
//
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// ManagedObjectObserver.swift
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// CoreDataStack
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//
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// Created by sxiaojian on 2021/2/8.
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//
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import Foundation
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import CoreData
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import Combine
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final public class ManagedObjectObserver {
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private init() { }
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}
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extension ManagedObjectObserver {
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public static func observe(object: NSManagedObject) -> AnyPublisher<Change, Error> {
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guard let context = object.managedObjectContext else {
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return Fail(error: .noManagedObjectContext).eraseToAnyPublisher()
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}
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return NotificationCenter.default.publisher(for: .NSManagedObjectContextObjectsDidChange, object: context)
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.tryMap { notification in
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guard let notification = ManagedObjectContextObjectsDidChangeNotification(notification: notification) else {
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throw Error.notManagedObjectChangeNotification
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}
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let changeType = ManagedObjectObserver.changeType(of: object, in: notification)
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return Change(
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changeType: changeType,
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changeNotification: notification
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)
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}
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.mapError { error -> Error in
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return (error as? Error) ?? .unknown(error)
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}
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.eraseToAnyPublisher()
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}
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}
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extension ManagedObjectObserver {
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private static func changeType(of object: NSManagedObject, in notification: ManagedObjectContextObjectsDidChangeNotification) -> ChangeType? {
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let deleted = notification.deletedObjects.union(notification.invalidedObjects)
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if notification.invalidatedAllObjects || deleted.contains(where: { $0 === object }) {
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return .delete
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}
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let updated = notification.updatedObjects.union(notification.refreshedObjects)
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if let object = updated.first(where: { $0 === object }) {
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return .update(object)
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}
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return nil
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}
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}
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extension ManagedObjectObserver {
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public struct Change {
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public let changeType: ChangeType?
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public let changeNotification: ManagedObjectContextObjectsDidChangeNotification
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init(changeType: ManagedObjectObserver.ChangeType?, changeNotification: ManagedObjectContextObjectsDidChangeNotification) {
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self.changeType = changeType
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self.changeNotification = changeNotification
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}
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}
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public enum ChangeType {
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case delete
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case update(NSManagedObject)
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}
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public enum Error: Swift.Error {
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case unknown(Swift.Error)
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case noManagedObjectContext
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case notManagedObjectChangeNotification
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}
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}
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