在@dfd的帮助下(参见
here
)通过将Combine导入我的UserNotes类,添加一个
objectWillChange
,还有电话
objectWillChange.send()
:
import Foundation
import UIKit
import CoreData
import Combine
class UserNotes: NSObject, ObservableObject {
var objectWillChange = PassthroughSubject<Void, Never>()
@Published var notes: [Note] = [] {
willSet {
objectWillChange.send()
}
}
var managedObjectContext: NSManagedObjectContext? = nil
var fetchedResultsController: NSFetchedResultsController<Note> {
if _fetchedResultsController != nil {
return _fetchedResultsController!
}
let fetchRequest: NSFetchRequest<Note> = Note.fetchRequest()
// Set the batch size to a suitable number.
fetchRequest.fetchBatchSize = 20
// Edit the sort key as appropriate.
let sortDescriptor = NSSortDescriptor(key: "unsecuredContent", ascending: false)
fetchRequest.sortDescriptors = [sortDescriptor]
// Edit the section name key path and cache name if appropriate.
// nil for section name key path means "no sections".
let aFetchedResultsController = NSFetchedResultsController(fetchRequest: fetchRequest,
managedObjectContext: self.managedObjectContext!,
sectionNameKeyPath: nil, cacheName: "Master")
aFetchedResultsController.delegate = self
_fetchedResultsController = aFetchedResultsController
do {
try _fetchedResultsController!.performFetch()
} catch {
// Replace this implementation with code to handle the error appropriately.
// fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
let nserror = error as NSError
fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
}
return _fetchedResultsController!
}
var _fetchedResultsController: NSFetchedResultsController<Note>? = nil
override init() {
super.init()
managedObjectContext = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
notes = fetchedResultsController.sections![0].objects as! [Note]
}
func createNewNote() {
let newNote = Note(context: managedObjectContext!)
// If appropriate, configure the new managed object.
newNote.unsecuredContent = UUID().uuidString // Just some random crap
// Save the context.
do {
try managedObjectContext!.save()
} catch {
// Replace this implementation with code to handle the error appropriately.
// fatalError() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
let nserror = error as NSError
fatalError("Unresolved error \(nserror), \(nserror.userInfo)")
}
}
}
extension UserNotes: NSFetchedResultsControllerDelegate {
func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {
notes = controller.sections![0].objects as! [Note]
}
}