Question 69258 in IOS Swift Question posted in
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How to get variable value of child view in parent view on SwiftUI? – Ios swift

I have one view "CancelRow", in which value of isSelected is changing

     struct CancelRow: View {
            @Binding var isSelected: Bool
        
            init(isSelected: Binding<Bool>) {
                self._isSelected = isSelected
            }
        
           @ViewBuilder var body: some View {
            HStack {
               Text(verbatim: "Hello, (isSelected)")
            }

            CustomCheckbox(checkboxType: .withTrailingLabel, 
             checkboxTitle: "", isActive: $canCancel, isSelected: $isSelected)
        }
        .onTapGesture {
                    isSelected.toggle()
                }
            }

I have another view i which i want to show button active or not based on "isSelected" from "CancelRow"

// AnotherVIew

CancelRow(isSelected: .constant(false))
    Spacer()
    SubmitButtonView(buttonTitle: title, buttonCallBack: {
        goToOtherScreen()
    }, isActive: isSelected ) // how to access this variable from  "CancelRow"
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2

Answers


  1. 0

    As mentioned in the comments, state should be owned by a parent view and then passed to the child views.

    In your case, you don’t actually need to use a custom initializer for CancelRow in the example you gave (you could rely on just the synthesized initializer), but as request, this uses an initializer.

    struct CancelRow: View {
    @Binding var isSelected: Bool
    
    init(isSelected: Binding<Bool>) {
        self._isSelected = isSelected
    }
    
    @ViewBuilder var body: some View {
        HStack {
            Text(verbatim: "Hello, (isSelected)")
            Button("Toggle") {
                isSelected.toggle()
            }
        }
    }
}

struct SubmitButtonView : View {
    var buttonTitle : String
    var buttonCallBack : () -> Void
    var isActive : Bool
    
    var body: some View {
        Text("Submit: (isActive ? "true" : "false")")
    }
}

struct ContentView: View {
    @State private var isSelected = false
    
    var title : String {
        "Title"
    }
    
    var body: some View {
        VStack {
            CancelRow(isSelected: $isSelected)
            SubmitButtonView(buttonTitle: title, buttonCallBack: {
                goToOtherScreen()
            }, isActive: isSelected )
        }
    }
    
    func goToOtherScreen() {
        print("Navigate")
    }
}
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  2. 0

    There is this concept of Source of truth. In oversimplified terms, you need to have a @State private var in one of your structs. If that @State private var holds any information some other struct would like to use, the second struct should have @Binding var and be initialised from the first struct with the value of @State private var.

    In code below struct AnotherView is the source of truth, it has @State private var, and other structs have @Binding and are initialised with value of that @State private var.

    struct AnotherView:

    @State private var isSelected = false

var body: some View {
    VStack {
        CancelRow(isSelected: $isSelected)
        
        Spacer()
        
        SubmitButtonView(isSelected: $isSelected)
    }
}

    struct CancelRow:

    @Binding var isSelected: Bool

var body: some View {
    Text(isSelected ? "I'm selected" : "I'm not selected")
}

    struct SubmitButtonView:

    @Binding var isSelected: Bool

var body: some View {
    Button {
        // do something on tap
    } label: {
        Text("Button text")
    }
}
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