Add Environmentobject in Swiftui 2.0

Add EnvironmentObject in SwiftUI 2.0

Try the following:

@main
struct TestApp: App {
    @StateObject var settings: Settings = ... // init here

    var body: some Scene {
        WindowGroup {
            ContentView()
                .environmentObject(settings)
        }
    }
}

SwiftUI: Using environment objects with Xcode 12/iOS 14 (-- How/where to place an object in the environment?)

You can create and inject it in scene of window group, like

@main
struct MyApp: App {
    @StateObject var userSettings = UserSettings()

    var body: some Scene {
        WindowGroup {
           ContentView().environmentObject(userSettings)
        }
    }
}

How to use EnvironmentObject in app file in SwiftUI

You can use it as regular property at that level and pass as environment down into view hierarchy if/when needed, like

struct ExampleApp: App {

    let userAuth = UserAuth()     // << here !!
    
    var body: some Scene {
        WindowGroup {
            switch userAuth.loginStatus {
            case .signedIn:
                ContentView()
                   .environmentObject(userAuth)    // << here !!
            case .signedOut:
                Text("Signed Out")
            }
        }
    }
}

How to manage @ObservedObject and @EnvironmentObject on same Struct?

SwiftUI 2.0

Make it @StateObject, like

struct MenuView: View {

@EnvironmentObject var order: Order
@StateObject var model = DetailsModel()
...

SwiftUI 1.0

Inject it externally via constructor (having for it own life-cycle)

struct MenuView: View {

@EnvironmentObject var order: Order
@ObservedObject var model: DetailsModel
...

A View.environmentObject(_:) for AppInformation may be missing as an ancestor of this view

So first of all, your example code is not working.

• Use @Published for your properties, then use Slider(value: $appInfo.duration, ...). This is because Slider is expecting a Binding (see https://developer.apple.com/documentation/swiftui/slider)
• Use the struct Settings_Previews outside of struct Settings

Below you will find the fixed version. Both running in previews and in Simulator.

To answer your question:

If you use Settings anywhere in your Code, you have to pass it an environmentObject of AppInformation (See ContentView). Since you did not provide any source code in context I assume thats where your error is.

Here is a working example:

import SwiftUI
import CoreData

class AppInformation: ObservableObject {
    @Published var duration = 0.0
    @Published var interval = 0.0
}

struct Settings: View {
    @EnvironmentObject var appInfo: AppInformation

    var body: some View {
        NavigationView {
            ZStack {
                VStack (spacing: 35){
                    HStack {
                        Text("Duration")
                            .font(.system(size: 23, weight: .bold, design: .rounded))
                            .padding(.leading, 25)
                        Spacer()

                        Slider(value: $appInfo.duration, in: 1...60, step: 1)
                            .padding([.trailing, .leading], 20)
                        Text("\(Int(appInfo.duration))")
                            .padding(.trailing, 30)
                            .font(.system(size: 23, weight: .medium, design: .rounded))
                    }
                    .padding(.top, 100)

                    HStack {
                        Text("Interval  ")
                            .font(.system(size: 23, weight: .bold, design: .rounded))
                            .padding(.leading, 25)
                        Spacer()

                        Slider(value: $appInfo.interval, in: 1...60, step: 1)
                            .padding([.trailing, .leading], 20)
                        Text("\(Int(appInfo.interval))")
                            .padding(.trailing, 30)
                            .font(.system(size: 23, weight: .medium, design: .rounded))

                    }
                    Spacer()
                }
            }
            .navigationTitle("Settings")
        }
    }
}

struct Settings_Previews: PreviewProvider {
    static var previews: some View {
        Settings()
            .environmentObject(AppInformation())
    }
}

struct ContentView: View {
    @ObservedObject var appInformation = AppInformation()

    var body: some View {
        Settings()
            .environmentObject(appInformation)
    }

}

Also here are some tips using SwiftUI:

• If you need to set padding on multiple edges you can use also use .padding([.trailing, .leading], 20)
• You should set the .navigationTitle("Settings") modifier on the outer child of the view - but within the NavigationView
• You can also set the .font modifier on the VStack or HStack, this would apply it to all children (including the Slider Label)

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