SwiftUI Picker onChange or equivalent?

Question

I want to change some other unrelated @State variable when a Picker gets changed but there is no onChanged and it\'s not possible to p

Answer 1

Here is what I just decided to use... (deployment target iOS 13)

struct MyPicker: View {
    @State private var favoriteColor = 0

    var body: some View {
        Picker(selection: $favoriteColor.onChange(colorChange), label: Text("Color")) {
            Text("Red").tag(0)
            Text("Green").tag(1)
            Text("Blue").tag(2)
        }
    }

    func colorChange(_ tag: Int) {
        print("Color tag: \(tag)")
    }
}

Using this helper

extension Binding {
    func onChange(_ handler: @escaping (Value) -> Void) -> Binding {
        return Binding(
            get: { self.wrappedValue },
            set: { selection in
                self.wrappedValue = selection
                handler(selection)
        })
    }
}

EDIT:

If your deployment target is set to iOS 14 or higher -- Apple has provided a built in onChange extension to View, which can be used like this instead (Thanks @Jeremy):

Picker(selection: $favoriteColor, label: Text("Color")) {
    // ..
}
.onChange(of: favoriteColor) { print("Color tag: \($0)") }