Not able to use the Toggle Switch with if else conditions in swift ui-CodePudding

I am not able to access use the switch. I want if the switch is on, it should come up with a text field and if it is off the value of the variable should be zero. Can anyone help me with this. I have tried to use two different methods. One by using .Onchange and one without using .Onchange. When I use .Onchange, it comes up with a waning that the result of text field is unused. And when I don't use .onAppear it doesn't accept (userSettings.load = 0) but the text field works fine then. I don't understand what I am doing wrong here.The variables are defined as :

struct TwoView: View {
    @EnvironmentObject var userSettings: UserSettings
    @State var load: Bool = false
    
    var body: some View {
        NavigationView {
            VStack {
                Form {
                    Toggle("Casual loading", isOn: $load)
                        .onChange(of: load) { value in
                            if load == false
                            {
                                userSettings.loadrate = 0
                            }
                            else
                            {
                                TextField("Casual Loading", value: $userSettings.loadrate, format: .number)
                            }
                        }
                }
            }
        }
    }
}

class UserSettings: ObservableObject
{
    @Published var loadrate = Float()
}

CodePudding user response：

Right now, you're using TextField outside of the view hierarchy, and just inside the onChange. In fact, as you mentioned, Xcode is giving you a warning about the fact that it is unused.

To solve this, you can use an if clause inside the hierarchy itself:

struct ContentView : View {
    var body: some View {
        TwoView().environmentObject(UserSettings())
    }
}

struct TwoView: View {
    @EnvironmentObject var userSettings: UserSettings
    @State var load: Bool = false
    
    var body: some View {
        NavigationView {
            VStack {
                Form {
                    Toggle("Casual loading", isOn: $load)
                        .onChange(of: load) { value in
                            //only imperative, non-View hierarchy code should go in this block
                            if load == false
                            {
                                userSettings.loadrate = 0
                            }
                        }
                    if load { //<-- Here
                        TextField("Casual Loading", value: $userSettings.loadrate, format: .number)
                    }
                }
            }
        }
    }
}

class UserSettings: ObservableObject
{
    @Published var loadrate = Float()
}

CodePudding user response：

TextField is a view element and it shouldn't be inside a closure. It should be a child of a view. Similarly, assignment is not a view element, so it is not accepted to be in a view.

So, what you need to do is put userSettings.loadrate = 0 into .onChange, and put TextField outside .onChange.

I'm not sure what exactly is your expected result, but here is an example.

NavigationView {
    VStack {
        Form {
            Toggle("Casual loading", isOn: $load)
                .onChange(of: load) { value in
                    // Assignment should be inside a closure
                    if load == false {
                        userSettings.loadrate = 0
                    }
                }
            if load == true {
                // View element should be a child of a view.
                TextField("Casual Loading", value: $userSettings.loadrate, format: .number)
            }
        }
    }
}