SwiftUI @State var initialization issue

Question

I would like to initialise the value of an @State var in SwiftUI trough the init() method of a Struct, so it can take the proper text

Answer 1

SwiftUI doesn't allow you to change @State in the initializer but you can initialize it.

Remove the default value and use _fullText to set @State directly instead of going through the property wrapper accessor.

@State var fullText: String // No default value of ""

init(letter: String) {
    _fullText = State(initialValue: list[letter]!)
}

Answer 2

The answer of Bogdan Farca is right for this case but we can't say this is the solution for the asked question because I found there is the issue with the Textfield in the asked question. Still we can use the init for the same code So look into the below code it shows the exact solution for asked question.

struct StateFromOutside: View {
    let list = [
        "a": "Letter A",
        "b": "Letter B",
        // ...
    ]
    @State var fullText: String = ""

    init(letter: String) {
        self.fullText = list[letter]!
    }

    var body: some View {
        VStack {
            Text("\(self.fullText)")
            TextField("Enter some text", text: $fullText)
        }
    }
}

And use this by simply calling inside your view

struct ContentView: View {
    var body: some View {
        StateFromOutside(letter: "a")
    }
}

Answer 3

I would try to initialise it in onAppear.

struct StateFromOutside: View {
    let list = [
        "a": "Letter A",
        "b": "Letter B",
        // ...
    ]
    @State var fullText: String = ""

    var body: some View {
        TextField($fullText)
             .onAppear {
                 self.fullText = list[letter]!
             }
    }
}

Or, even better, use a model object (a BindableObject linked to your view) and do all the initialisation and business logic there. Your view will update to reflect the changes automatically.

---

Update: BindableObject is now called ObservableObject.