Data disappears when the app reloads - Date planner on Swift Playgrounds | SwiftUI

Question

MohamedElshaffei OP

Created May ’22

Replies 1

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Participants 2

Hi there, I just started coding my first app in SwiftUI

I am recreating the date planner app, an app on Swift Playgrounds, and I can’t seem to make the data persists in a view programmatically.

I have created an observable class that contains a published property of type [Event] to store a Events in an array with functions that can add & remove events from it.

class EventData: ObservableObject {

    @Published var events: [Event] = [
        Event(symbol: "gift.fill",
              color: .red,
              name: "Kiko's Birthday",
              tasks: [EventTasks(text: "Guava kombucha"),
                      EventTasks(text: "Paper cups and plates"),
                      EventTasks(text: "Cheese plate"),
                      EventTasks(text: "Party poppers"),
                     ],
              date: Date.roundedHoursFromNow(60 * 60 * 24 * 30)),

        Event(symbol: "theatermasks.fill",
              color: .yellow,
              name: "mo’s promotion”
              tasks: [EventTasks(text: "Buy new tux"),
                      EventTasks(text: "Get tickets"),
                      EventTasks(text: "Pick up Carmen at the airport and bring her to the show"),] ,
              date: Date.roundedHoursFromNow(60 * 60 * 22)) ]

    func delete(_ event: Event) {
        events.removeAll { $0.id == event.id }
    }

    func add(_ event: Event) {
        events.append(event)
    }

}

I then created an instance of the class in the app root wrapped by the @stateobject property and passed it into the environment so the data becomes accessible to all views.

import SwiftUI

@main

struct MyApp: App {
    @StateObject private var eventData = EventData()

    var body: some Scene {
        WindowGroup{
            NavigationView{
                EventList()
                .foregroundColor(.green)
                }

            .environmentObject(eventData)
        }

    }

}

I then created a list that constructs the main view for the app from the array stored in Event Data class. I also created an editor in a modal sheet that allows users to add a new event, once triggered it automatically creates a new event and shows it into the list.

MO’s Planner.png

The problem is when the app reloads this data disappears as if it’s not stored in the array. And the only data that persists is the events that I added manually in the array.

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Answer 1

DelawareMathGuy OP

May ’22

hi,

when you say

I have created an observable class that contains a published property of type [Event] to store a Events in an array ...

what you really mean by store is that you have an in-memory array of type [Event] and you have appended a new Event to that in-memory array; but you have not persisted the data outside of your app.

common solutions to persist data across launches (of an iOS application) include:

writing data to a file in the user's Document's directory
writing data to UserDefaults (not ideal, and certainly not scalable)
saving data to Core Data (perhaps with a CloudKit component)
writing data directly to CloudKit

you will need to read up on these solutions. i highly recommend Paul Hudson's 100 Days of SwiftUI course (https://www.hackingwithswift.com/100/swiftui), or 100 Days of Swift (if you are using UIKit), where several of these methods are described.

good luck,

DMG

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