How can I trigger an action when a swiftUI toggle() is toggled?

iOS 14+

If you’re using iOS 14 and higher you can use onChange:

struct ContentView: View {
    @State private var isDisplayed = false
    
    var body: some View {
        Toggle("", isOn: $isDisplayed)
            .onChange(of: isDisplayed) { value in
                // action...
                print(value)
            }
    }
}