How do I resolve Picker selection via Proxy? - binding

Question

Scenario: I want to handle the selection event whilst harvesting the selected item via a Picker.
This is in reference to an introduction discussion to the Picker Proxy.
This is what I have so far. I can't get the event handler to fire/activate/run doSomething().
import SwiftUI
struct ContentView: View {
var body: some View {
GeometryReader { _ in
VStack {
Text("PickerView")
.font(.headline)
.foregroundColor(.gray)
.padding(.top, 10)
Picker("test", selection: Binding(get: { "" }, set: { _ in
doSomething()
})) {
Text("Hello").id("1")
Text("Uncle").id("2")
Text("Ric").id("3")
}.labelsHidden()
}.background(RoundedRectangle(cornerRadius: 10)
.foregroundColor(Color.white).shadow(radius: 1))
}
.padding()
}
func doSomething() {
print("Hello Something!")
}
}
Note:
I don't know what to do with the get{} so I put a null string there to satisfy the compiler.
I tried evaluating the closure parameter (via print(*closure parameter*)) but got no value, so I placed a _ placeholder to satisfy the compiler.
How to I harvest the selection?
The closure parameter doesn't appear to work here; hence the placeholder. There aren't many examples to follow.

Answer 1

Here is a possible solution:
struct ContentView: View {
// extract picker values for easier access
private let items = ["Hello", "Uncle", "Ric"]
// store the currently selected value
#State private var selection = 0
// custom binding for the `selection`
var binding: Binding<Int> {
.init(get: {
selection
}, set: {
selection = $0
doSomething() // call another function after the `selection` is set
})
}
var body: some View {
Picker("test", selection: binding) {
ForEach(0 ..< items.count) { index in // use `ForEach` to quickly generate picker values
Text(items[index])
.tag(index) // use `tag` instead of `id`
}
}
.labelsHidden()
}
func doSomething() {
print("Hello Something!")
}
}

Answer 2

Discussion:
You can use onChange to trigger a side effect as the result of a value changing, such as an Environment key or a Binding...
(Apple doc.)
struct ContentView: View {
#State
private var selection = 0
let items = ["Hello", "Uncle", "Ric"]
var body: some View {
VStack {
Picker("", selection: $selection) {
ForEach(0..<items.count) {
Text(items[$0])
.tag($0)
}
}
.onChange(of: selection) { _ in
print("Hello Something!")
}
}
}
}