Convert a variable into JSON (Lunch Card expansion)

You need to call cardsInfo.saveCards(), where cardsInfo is the right instance of CardsInfo, maybe some action closure in CardsView.

1. Another action in the Create button in AddView:

Code Block 
Button(action: {
	cardsInfo.add()
	cardsInfo.saveCards()
	sheetInfo.showSheetView = false
}) {
	Text("Create")
		.bold()
}
.disabled(self.cardsInfo.newCard.name.isEmpty    self.cardsInfo.newCard.id.isEmpty    self.cardsInfo.newCard.cname.isEmpty)
.foregroundColor(.white)
.padding()
.padding(.horizontal, 100)
.background(Color.accentColor)
.cornerRadius(10)

Code Block 
private func onDelete(offsets: IndexSet) {
	self.presentMode.toggle()
	cardsInfo.cards.remove(atOffsets: offsets)
	cardsInfo.saveCards()
}
    
private func onMove(source: IndexSet, destination: Int) {
	cardsInfo.cards.move(fromOffsets: source, toOffset: destination)
	cardsInfo.saveCards()
}

I assume I'd need that to load the saved cards, but I don't know where I'd put that during initial launch.

Code Block 
.onAppear(perform: cardsInfo.loadCards)

Code Block 
.onAppear {
	cardsInfo.loadCards()
}

Neither worked.

Code Block 
//
//  Info.swift
//  Lunch Card (iOS)
//
//  Created by Joshua Srery on 12/21/20.
//  Additional code by OOPer on Apple Developer Forums
//
import Foundation
struct CardInfo: Identifiable, Codable {
    var name: String = ""
    var id: String = ""
    var cname: String = ""
//    var code: String = ""
}
class CardsInfo: ObservableObject {
    @Published var newCard: CardInfo = CardInfo()
    @Published var cards: [CardInfo] = []
    
    func add() {
        cards.append(newCard)
    }
}
extension CardsInfo {
    var dataUrl: URL {
        FileManager.default.urls(for: .documentDirectory, in: .userDomainMask)[0]
            .appendingPathComponent("cards.json")
    }
    
    func saveCards() {
        do {
            let data = try JSONEncoder().encode(cards)
            try data.write(to: dataUrl, options: .atomic)
        } catch {
            print(error)
        }
    }
    
    func loadCards() {
        do {
            if FileManager.default.fileExists(atPath: dataUrl.path) {
                return
            }
            let data = try Data(contentsOf: dataUrl)
            let cards = try JSONDecoder().decode([CardInfo].self, from: data)
            self.cards = cards
        } catch {
            print(error)
        }
    }
}
class SheetInfo: ObservableObject {
    @Published var showSheetView = false
}

Code Block 
//
//  CardsView.swift
//  Lunch Card (iOS)
//
//  Created by Joshua Srery on 12/17/20.
//  Additional code by OOPer on Apple Developer Forums
//
import SwiftUI
struct Card: Identifiable {
    let id = UUID()
    let title: String
}
struct CardsView: View {
    @StateObject var cardsInfo = CardsInfo()
    @StateObject var sheetInfo = SheetInfo()
    @State private var editMode = EditMode.inactive
    @State var presentMode = false
    
    var body: some View {
        NavigationView {
            List {
                ForEach(cardsInfo.cards) { card in
                    NavigationLink(destination: CardFullView(cname: card.cname, name: card.name, id: card.id)) {
                        CardRow(cname: card.cname, name: card.name, id: card.id)
                        
                    }
                }
                .onDelete(perform: onDelete)
                .onMove(perform: onMove)
            }.listStyle(PlainListStyle())
            .navigationTitle("Cards")
            .toolbar {
                ToolbarItem(placement: .navigationBarLeading) {
                    EditButton()
                }
                ToolbarItem(placement: .navigationBarTrailing) {
                    Button(action: {
                        self.sheetInfo.showSheetView.toggle()
                    }) {
                        Image(systemName: "plus")
                    }
                }
            }
            .environment(\.editMode, $editMode)
            .sheet(isPresented: $sheetInfo.showSheetView) {
                AddView(cardsInfo: cardsInfo, sheetInfo: sheetInfo)
            }
            .onAppear {
                cardsInfo.loadCards() // <- Preferred Placement
            }
        }
    }
    
    private func onDelete(offsets: IndexSet) {
        self.presentMode.toggle()
        cardsInfo.cards.remove(atOffsets: offsets)
        cardsInfo.saveCards()
    }
    
    private func onMove(source: IndexSet, destination: Int) {
        cardsInfo.cards.move(fromOffsets: source, toOffset: destination)
        cardsInfo.saveCards()
    }
}

Here's Info.swift and CardsView:

Code Block 
    func loadCards() {
        do {
            if !FileManager.default.fileExists(atPath: dataUrl.path) { //<- Please do not miss `!`
                return
            }
            let data = try Data(contentsOf: dataUrl)
            let cards = try JSONDecoder().decode([CardInfo].self, from: data)
            self.cards = cards
        } catch {
            print(error)
        }
    }

The first is syntactically bad in Swift,

Sorry for taking your time.