SwiftUI.State: .init(wrappedValue:) vs. .init(initialValue:): what's the difference?

[Lantua]

SwiftUI views don't really have concepts of lifetime. So it's hard to say when a view is recreated and needs to reload the initial values.

If your reload events coincide with the view appearances though, you can just use onAppear.

[young (rtSwift)]

You can override @State value by giving the view a different id():

import SwiftUI

/// You can override @State value as long as you give it a new id!!
struct FooFooPicker: View {
    @State private var selection: Int

    init(_ val: Int) {
        _selection = State(wrappedValue: val)
    }

    var body: some View {
        VStack {
            Text("Selection: \(selection)")
            Picker("Numbers", selection: $selection) {
                ForEach(0...5, id: \.self) { number in
                    Text(verbatim: "\(number)").tag(number)
                }
            }
        }
    }
}


struct PickerDefaultSettable: View {
    @State var defaultOverride = 0
    @State var id = 0
    var body: some View {
        VStack {
            FooFooPicker(defaultOverride)
                .id(id)     // invalidate the view state
            Text("DefaultOverride: \(defaultOverride)")
            VStack {
                ForEach(0...5, id: \.self) { number in
                    Button("\(number)") {
                        defaultOverride = number
                        id += 1     // generate a new id
                    }
                }
            }
        }
    }
}

struct PickerDefaultSettable_Previews: PreviewProvider {
    static var previews: some View {
        PickerDefaultSettable()
    }
}