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Day 95 - or How to pass data between views

Forums > 100 Days of SwiftUI

Hi All, I've got a skeleton of an app, but it's not quite working yet.

I have a view that should display a list of past dice rolls. it's using a ForEach in a List. But the List is always empty.

I am uncertain what I have setup incorrectly, I am not sure if it's my view or my data model. See below or the gitHub link

DiceRolls.swift

The data model

import SwiftUI

struct SingleDiceRoll: Identifiable, Codable, Hashable {
    let id = UUID()
    let dice1: Int
    let dice2: Int
}

class DiceRolls: ObservableObject {
    @Published var multipleDiceRolls: [SingleDiceRoll]

    init() {
        multipleDiceRolls = []
    }
}

PastRollsView.swift

list view of previous dice rolls

import SwiftUI

struct PastRollsView: View {
    @ObservedObject var diceRolls: DiceRolls
    var body: some View {
        List {
            ForEach(diceRolls.multipleDiceRolls) { roll in
                Text("Foo \(roll.dice1)")
            }
        }
    }
}

struct PastRollsView_Previews: PreviewProvider {
    static var previews: some View {
        PastRollsView(diceRolls: DiceRolls())
    }
}

ContentView.swift

View to roll dice and see current roll

import SwiftUI

struct ContentView: View {
    @State private var dieOne = 0
    @State private var dieTwo = 0
    @ObservedObject var diceRolls: DiceRolls

    var body: some View {
        VStack {
            Button(action: rollDice, label: { Text("Roll Dice")})
                .padding()

            Text("Dice One: \(dieOne)")
                .padding()
            Text("Dice Two: \(dieTwo)")
        }
    }

    func rollDice() {
        let dice1 = Int.random(in: 1...6)
        let dice2 = Int.random(in: 1...6)

        dieOne = dice1
        dieTwo = dice2
        diceRolls.multipleDiceRolls.append(SingleDiceRoll(dice1: dice1, dice2: dice2))

    }
}

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

MainTabView.swift

A TabView controller

import SwiftUI
enum Tab {
    case rollView, pastRollView
}

struct MainTabView: View {
    @State private var selectedTab = Tab.rollView
    @ObservedObject var diceRolls: DiceRolls
    var body: some View {
        TabView {
            ContentView(diceRolls: DiceRolls())
                .tabItem {
                    Image(systemName: "gamecontroller")
                    Text("Roll Dice")
            }
            .tag(Tab.rollView)

            PastRollsView(diceRolls: diceRolls)
                .tabItem {
                    Image(systemName: "list.dash")
                    Text("past rolls")
            }
            .tag(Tab.pastRollView)
        }

    }
}

struct MainTabView_Previews: PreviewProvider {
    static var previews: some View {
        MainTabView(diceRolls: DiceRolls())
    }
}

1      

Hey mate,

Hopefully you figured out by now but if not here's the gig: In your MainTabView you should declare an instance of the diceRolls and use that for the parameter of your ContentView(diceRolls: ...) like this:

struct MainTabView: View {
    @State private var selectedTab = Tab.rollView
    @ObservedObject var diceRolls = DiceRolls()
    var body: some View {
        TabView {
            ContentView(diceRolls: diceRolls)
                .tabItem {
                    Image(systemName: "gamecontroller")
                    Text("Roll Dice")
            }
            .tag(Tab.rollView)

            PastRollsView(diceRolls: diceRolls)
                .tabItem {
                    Image(systemName: "list.dash")
                    Text("past rolls")
            }
            .tag(Tab.pastRollView)
        }

    }
}

Hope it helps. Good luck!

1      

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