Passing one StateObject class of one view to another StateObject class of a different view in SwiftU-CodePudding

I have two views each with their own class. The first view has an @StateObject of class "DataClass" that initializes a simple struct DataStruct:

 struct View1 : View {
    @StateObject var dataToPass = DataClass()
    
    var body: some View {
        NavigationView{
            ZStack{
                NavigationLink(destination: View2(data: dataToPass)){
                    Text("Navigation Link to View2")
                }
            }
        }
    }
 }

 struct dataStruct {
    var variable1 : String
    var variable2 : String
 }

 class DataClass : ObservableObject {
    var data : dataStruct
    init(){
        data = dataStruct(variable1: "1", variable2: "2")
    }
 }

I'm trying to keep this same instance of the DataClass/dataStruct and pass it on to View2 and its View2Class:

 struct View2: View {
    
    @ObservedObject var data : DataClass
    
    @StateObject var game = View2Class(data: data)
    
    var body: some View {
        Text("Hello")
    }
 }

 class View2Class : ObservableObject {
    @ObservedObject var data : DataClass
    
    init(data : DataClass){
        self.data = data
    }
 }

I want it so that there is only ever one instance/initialization of dataStruct and thus dataClass and View2Class has access to it. View2Class must remain a StateObject. As of right now I am getting an error on the declaration of View2's StateObject: "Cannot use instance member 'data' within property initializer; property initializers run before 'self' is available." I'm sure it is an easy conceptual fix that I am not understanding right now. Thank you!

CodePudding user response：

To fix the error ("Cannot use instance member 'data'...") try something like this:

 struct View1 : View {
    @StateObject var dataToPass = DataClass()
    
    var body: some View {
        NavigationView{
            ZStack{
                NavigationLink(destination: View2(data: dataToPass, game: View2Class(data: dataToPass))){
                    Text("Navigation Link to View2")
                }
            }
        }
    }
 }

 // ...

 struct View2: View {
    @ObservedObject var data: DataClass
    @StateObject var game: View2Class
    
    var body: some View {
        Text("Hello")
    }
 }

CodePudding user response：

You cannot use data to declare game, because data is not "available" before View2 is setup. That is the reason you get the error.

Try this approach, using @Published in the ObservableObject classes, and passing DataStruct from DataClass to your View2Class with a function in .onAppear {...}:

struct DataStruct {
    var variable1: String
    var variable2: String
 }

class DataClass: ObservableObject {
    @Published var data = DataStruct(variable1: "1", variable2: "2")
}

struct View2: View {
    @ObservedObject var dataClass: DataClass
    @StateObject var game = View2Class()
    
    var body: some View {
        Text("Hello")
            .onAppear {
                game.setData(dataClass.data)
            }
    }
}

class View2Class: ObservableObject {
    @Published var data: DataStruct?

    func setData(_ data: DataStruct){
        self.data = data
    }
}