Swift static value stuck at original value - ios

Question

Can someone tell me why my static variable isn't changing when I use a += on it? I have been stuck on this bug for a while.
#State static var counter:Int = 2
#State static var increment:Int = 1
var body: some View {
NavigationView {
VStack {
Text("Value: " + String(ContentView.counter))
Button(action: {
ContentView.counter += ContentView.increment
print(ContentView.counter)

Answer 1

If you want to share state between different instances of your view, you should inject said state as a Binding rather than declaring an #State static property inside the View.
#State properties should only be updated from inside the (body of the) view itself, which isn't the case if you declare an #State property as static. To ensure the update can only happen from inside the View, all #State properties must be private (or at the very least private(set)).
Not sure how exactly you create different instances of your view, but here's an example of how you could introduce shared state between them in a correct way:
struct Cell: View {
#Binding private var counter: Int
#Binding private var increment: Int
init(counter: Binding<Int>, increment: Binding<Int>) {
self._counter = counter
self._increment = increment
}
var body: some View {
VStack {
Text("Value: \(counter)")
Button("Increment by \(increment)", action: { counter += increment })
}
}
}
struct Counter: View {
#State private var counter: Int = 2
#State private var increment: Int = 1
var body: some View {
VStack {
Cell(counter: $counter, increment: $increment)
Cell(counter: $counter, increment: $increment)
Cell(counter: $counter, increment: $increment)
}
}
}