swift - SwiftUI: deleted row from List keeps re-appearing

Question

I have the following view which displays notifications to the user:

struct NotificationContentView: View {
    @State private var notifications = UploadNotificationManager.shared.notifications
    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    
    private lazy var context: NSManagedObjectContext = {
        return appDelegate.persistentContainer.viewContext
    }()
    
    var body: some View {
        List {
            if let notifications = UploadNotificationManager.shared.notifications {
                ForEach(notifications, id: .self) { notification in
                    if let text = UploadNotificationManager.shared.notificationText(notifcation: notification) {
                        VStack(alignment: .trailing, spacing: 6) {
                            HStack {
                                Image(systemName: "xmark.circle.fill").foregroundColor(Color(UIColor.i6.alert))
                                Text(text).font(.system(size: 14))
                            }
                            Text("3 mins ago").font(.system(size: 10)).foregroundColor(Color(UIColor.i6.blue.withAlphaComponent(0.8)))
                        }
                    }
                }
                .onDelete(perform: delete)
            }
        }.cornerRadius(15).shadow(radius: 5).shadow(color: .gray, radius: 3, x: 2, y: 2).frame(width: 400, height: 350, alignment: .center)
    }
    
    func delete(at offsets: IndexSet) {
        guard let index = Array(offsets).first else { return }
        notifications?.remove(at: index)
        notifications![0].dismissed = true
        appDelegate.saveContext()
    }
}

However, the delete method is not working. Whilst the row temporarily disappears, it immediately comes back into view. What am I doing wrong here?

Code for UploadNotificationManager class:

class UploadNotificationManager {
    var notifications: [UploadNotificationCD]?
    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    
    static let shared = UploadNotificationManager()
    
    init() {
        getNotifications()
    }
    
    func getNotifications() {
        let context = appDelegate.persistentContainer.viewContext
        notifications = context.fetch(UploadNotificationCD.self)
    }
    
    func notificationText(notifcation: UploadNotificationCD) -> String? {
        guard let code = notifcation.fuelSheet?.flightNumber else { return nil }
        if notifcation.flightValid == false {
            return "Unable to create order for flight (code) - invalid flight"
        } else if notifcation.successfullyUploaded == false {
            return "Unable to create order for flight (code)"
        } else {
            return "Successfully uploaded order for flight (code)"
        }
    }
}

question from:https://stackoverflow.com/questions/65848934/swiftui-deleted-row-from-list-keeps-re-appearing

Answer 1

You have to delete the object from the view context. Create a function in your UploadNotificationManager that can delete a notification from your app's view context and pass it the notification from the delete function that your view calls on delete.

extension UploadNotificationManager {
    func deleteNotification(notifcation: UploadNotificationCD) {
        let context = appDelegate.persistentContainer.viewContext
        context?.delete(notifcation)
        appDelegate.saveContext()
    }
}


struct NotificationContentView: View {
    ...
    func delete(at offsets: IndexSet) {
        guard let index = Array(offsets).first else { return }
        UploadNotificationManager.shared.deleteNotification(notification: notifications[index])
    }
}