Hi! I would be grateful for any anvice how to fix my Habit Tracker project. At the moment I'm able to update how many times the activity was done and it changes when I go back to the list but I cannot see any updates on the Activity View in real time (In the "Completed XXX times" Text View). Here is my code:

//
//  ContentView.swift
//  HabitTracker
//
//  Created by Anna Nakayama on 2020/12/04.
//

import SwiftUI

struct Activity: Identifiable, Codable {
    private(set) var id = UUID()
    let name: String
    let description: String
    var doneCount: Int
}

class Activities: ObservableObject {
    @Published var activities: [Activity] {
        didSet {
            let encoder = JSONEncoder()
            if let encoded = try? encoder.encode(activities) {
                UserDefaults.standard.set(encoded, forKey: "Activities")
            }
        }
    }

    init() {
        if let activities = UserDefaults.standard.data(forKey: "Activities") {
            let decoder = JSONDecoder()
            if let decoded = try? decoder.decode([Activity].self, from: activities) {
                self.activities = decoded
                return
            }
        }
        self.activities = []
    }

    func updateDoneCount(index: Int) {
        activities[index].doneCount += 1
    }
}

struct ContentView: View {
    @ObservedObject var myActivities = Activities()
    @State private var showingAddActivity = false

    var body: some View {
        NavigationView {
            List {
                ForEach(myActivities.activities.indices, id: \.self) { index in
                    NavigationLink(destination: ActivityView( activities: myActivities, index: index)) {
                        HStack {
                            VStack(alignment: .leading) {
                                Text(self.myActivities.activities[index].name)
                                    .font(.headline)
                            }
                            Spacer()
                            Text("Completed \(self.myActivities.activities[index].doneCount) times")
                        }
                    }
                }
                .onDelete(perform: removeActivity)
            }
            .navigationTitle("Activity Tracker")
            .navigationBarItems(leading: EditButton(), trailing: Button(action: {
                self.showingAddActivity = true
            }) {    
                Image(systemName: "plus")
            })
            .sheet(isPresented: $showingAddActivity) {
                AddView(activities: self.myActivities)
            }
        }
    }

    func removeActivity(at offsets: IndexSet) {
        self.myActivities.activities.remove(atOffsets: offsets)
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

//
//  ActivityView.swift
//  HabitTracker
//
//  Created by Anna Nakayama on 2020/12/07.
//

import SwiftUI

struct ActivityView: View {
    var activities: Activities
    var index: Int

    var body: some View {
        VStack(alignment: .center) {
            Text(activities.activities[index].name)
                .font(.title)
                .foregroundColor(.purple)
                .padding()
            Text(activities.activities[index].description)
            Text("Completed \(activities.activities[index].doneCount) times")
                .padding()

            Button(action:{ self.activities.updateDoneCount(index: self.index)}) {
                Text("Complete!")
                    .padding()
                    .foregroundColor(.white)
                    .background(Color.purple)
                    .font(.title)
                    .cornerRadius(40)
            }
            .navigationBarTitle(Text("My activity"), displayMode: .inline)
        }
    }
}

struct ActivityView_Previews: PreviewProvider {
    static var previews: some View {
        let activities = Activities()
        ActivityView(activities: activities, index: 0)
    }
}

@delawaremathguy Thanks so much for your help! Worked like a charm :)